diff --git a/pkg/config/BUILD.bazel b/pkg/config/BUILD.bazel
index fc0a64a903..fc6c57bd61 100644
--- a/pkg/config/BUILD.bazel
+++ b/pkg/config/BUILD.bazel
@@ -13,6 +13,7 @@ go_library(
         "deployment_lambda.go",
         "deployment_terraform.go",
         "duration.go",
+        "event_watcher.go",
         "image_watcher.go",
         "piped.go",
         "replicas.go",
@@ -38,6 +39,7 @@ go_test(
         "deployment_kubernetes_test.go",
         "deployment_terraform_test.go",
         "deployment_test.go",
+        "event_watcher_test.go",
         "image_watcher_test.go",
         "piped_test.go",
         "replicas_test.go",
diff --git a/pkg/config/config.go b/pkg/config/config.go
index 0dd090312d..7a8584592e 100644
--- a/pkg/config/config.go
+++ b/pkg/config/config.go
@@ -64,6 +64,8 @@ const (
 	KindAnalysisTemplate Kind = "AnalysisTemplate"
 	// KindImageWatcher represents configuration for Repo Watcher.
 	KindImageWatcher Kind = "ImageWatcher"
+	// KindEventWatcher represents configuration for Event Watcher.
+	KindEventWatcher Kind = "EventWatcher"
 )
 
 var (
@@ -87,6 +89,7 @@ type Config struct {
 	ControlPlaneSpec     *ControlPlaneSpec
 	AnalysisTemplateSpec *AnalysisTemplateSpec
 	ImageWatcherSpec     *ImageWatcherSpec
+	EventWatcherSpec     *EventWatcherSpec
 
 	SealedSecretSpec *SealedSecretSpec
 }
@@ -150,6 +153,10 @@ func (c *Config) init(kind Kind, apiVersion string) error {
 		c.ImageWatcherSpec = &ImageWatcherSpec{}
 		c.spec = c.ImageWatcherSpec
 
+	case KindEventWatcher:
+		c.EventWatcherSpec = &EventWatcherSpec{}
+		c.spec = c.EventWatcherSpec
+
 	default:
 		return fmt.Errorf("unsupported kind: %s", c.Kind)
 	}
diff --git a/pkg/config/event_watcher.go b/pkg/config/event_watcher.go
new file mode 100644
index 0000000000..834def137b
--- /dev/null
+++ b/pkg/config/event_watcher.go
@@ -0,0 +1,136 @@
+// Copyright 2021 The PipeCD Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package config
+
+import (
+	"fmt"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+)
+
+type EventWatcherSpec struct {
+	Events []EventWatcherEvent `json:"events"`
+}
+
+// EventWatcherEvent defines which file will be replaced when the given event happened.
+type EventWatcherEvent struct {
+	// The event name.
+	Name string `json:"name"`
+	// Additional attributes of event. This can make an event definition
+	// unique even if the one with the same name exists.
+	Labels map[string]string `json:"labels"`
+	// List of places where will be replaced when the new event matches.
+	Replacements []EventWatcherReplacement `json:"replacements"`
+}
+
+type EventWatcherReplacement struct {
+	// The path to the file to be updated.
+	File string `json:"file"`
+	// The yaml path to the field to be updated. It requires to start
+	// with `$` which represents the root element. e.g. `$.foo.bar[0].baz`.
+	YAMLField string `json:"yamlField"`
+	// TODO: Support JSONField to replace values in json format
+	// TODO: Support HCLField to replace values in HCL format
+}
+
+// LoadEventWatcher gives back parsed EventWatcher config after merging config files placed under
+// the .pipe directory. With "includes" and "excludes", you can filter the files included the result.
+// "excludes" are prioritized if both "excludes" and "includes" are given. ErrNotFound is returned if not found.
+func LoadEventWatcher(repoRoot string, includes, excludes []string) (*EventWatcherSpec, error) {
+	dir := filepath.Join(repoRoot, SharedConfigurationDirName)
+	files, err := ioutil.ReadDir(dir)
+	if os.IsNotExist(err) {
+		return nil, ErrNotFound
+	}
+	if err != nil {
+		return nil, fmt.Errorf("failed to read %s: %w", dir, err)
+	}
+
+	// Start merging events defined across multiple files.
+	spec := &EventWatcherSpec{
+		Events: make([]EventWatcherEvent, 0),
+	}
+	filtered, err := filterEventWatcherFiles(files, includes, excludes)
+	if err != nil {
+		return nil, fmt.Errorf("failed to filter event watcher files at %s: %w", dir, err)
+	}
+	for _, f := range filtered {
+		if f.IsDir() {
+			continue
+		}
+		path := filepath.Join(dir, f.Name())
+		cfg, err := LoadFromYAML(path)
+		if err != nil {
+			return nil, fmt.Errorf("failed to load config file %s: %w", path, err)
+		}
+		if cfg.Kind == KindEventWatcher {
+			spec.Events = append(spec.Events, cfg.EventWatcherSpec.Events...)
+		}
+	}
+
+	if err := spec.Validate(); err != nil {
+		return nil, err
+	}
+
+	return spec, nil
+}
+
+// filterEventWatcherFiles filters the given files based on the given Includes and Excludes.
+// Excludes are prioritized if both Excludes and Includes are given.
+func filterEventWatcherFiles(files []os.FileInfo, includes, excludes []string) ([]os.FileInfo, error) {
+	if len(includes) == 0 && len(excludes) == 0 {
+		return files, nil
+	}
+
+	filtered := make([]os.FileInfo, 0, len(files))
+	useWhitelist := len(includes) != 0 && len(excludes) == 0
+	if useWhitelist {
+		whiteList := make(map[string]struct{}, len(includes))
+		for _, i := range includes {
+			whiteList[i] = struct{}{}
+		}
+		for _, f := range files {
+			if _, ok := whiteList[f.Name()]; ok {
+				filtered = append(filtered, f)
+			}
+		}
+		return filtered, nil
+	}
+
+	blackList := make(map[string]struct{}, len(excludes))
+	for _, e := range excludes {
+		blackList[e] = struct{}{}
+	}
+	for _, f := range files {
+		if _, ok := blackList[f.Name()]; !ok {
+			filtered = append(filtered, f)
+		}
+	}
+	return filtered, nil
+}
+
+func (s *EventWatcherSpec) Validate() error {
+	for _, e := range s.Events {
+		if e.Name == "" {
+			return fmt.Errorf("event name must not be empty")
+		}
+		if len(e.Replacements) == 0 {
+			return fmt.Errorf("there must be at least one replacement to an event")
+		}
+		// TODO: Consider merging events if there are events whose combination of name and labels is the same
+	}
+	return nil
+}
diff --git a/pkg/config/event_watcher_test.go b/pkg/config/event_watcher_test.go
new file mode 100644
index 0000000000..b540f0f0a0
--- /dev/null
+++ b/pkg/config/event_watcher_test.go
@@ -0,0 +1,217 @@
+// Copyright 2021 The PipeCD Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package config
+
+import (
+	"os"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestLoadEventWatcher(t *testing.T) {
+	want := &EventWatcherSpec{Events: []EventWatcherEvent{
+		{
+			Name: "app1-image-update",
+			Replacements: []EventWatcherReplacement{
+				{
+					File:      "app1/deployment.yaml",
+					YAMLField: "$.spec.template.spec.containers[0].image",
+				},
+			},
+		},
+		{
+			Name: "app2-helm-release",
+			Labels: map[string]string{
+				"repoId": "repo-1",
+			},
+			Replacements: []EventWatcherReplacement{
+				{
+					File:      "app2/.pipe.yaml",
+					YAMLField: "$.spec.input.helmChart.version",
+				},
+			},
+		},
+	}}
+
+	t.Run("valid config files given", func(t *testing.T) {
+		got, err := LoadEventWatcher("testdata", nil, []string{"README.md"})
+		assert.NoError(t, err)
+		assert.Equal(t, want, got)
+	})
+}
+
+func TestEventWatcherValidate(t *testing.T) {
+	testcases := []struct {
+		name             string
+		eventWatcherSpec EventWatcherSpec
+		wantErr          bool
+	}{
+		{
+			name: "no name given",
+			eventWatcherSpec: EventWatcherSpec{
+				Events: []EventWatcherEvent{
+					{
+						Replacements: []EventWatcherReplacement{
+							{
+								File:      "file",
+								YAMLField: "$.foo",
+							},
+						},
+					},
+				},
+			},
+			wantErr: true,
+		},
+		{
+			name: "no replacements given",
+			eventWatcherSpec: EventWatcherSpec{
+				Events: []EventWatcherEvent{
+					{
+						Name: "event-a",
+					},
+				},
+			},
+			wantErr: true,
+		},
+		{
+			name: "valid config given",
+			eventWatcherSpec: EventWatcherSpec{
+				Events: []EventWatcherEvent{
+					{
+						Name: "event-a",
+						Replacements: []EventWatcherReplacement{
+							{
+								File:      "file",
+								YAMLField: "$.foo",
+							},
+						},
+					},
+				},
+			},
+			wantErr: false,
+		},
+	}
+	for _, tc := range testcases {
+		t.Run(tc.name, func(t *testing.T) {
+			err := tc.eventWatcherSpec.Validate()
+			assert.Equal(t, tc.wantErr, err != nil)
+		})
+	}
+}
+
+type fakeFileInfo struct {
+	name string
+}
+
+func (f *fakeFileInfo) Name() string { return f.name }
+
+// Below methods are required to meet the interface.
+func (f *fakeFileInfo) Size() int64        { return 0 }
+func (f *fakeFileInfo) Mode() os.FileMode  { return 0 }
+func (f *fakeFileInfo) ModTime() time.Time { return time.Now() }
+func (f *fakeFileInfo) IsDir() bool        { return false }
+func (f *fakeFileInfo) Sys() interface{}   { return nil }
+
+func TestFilterEventWatcherFiles(t *testing.T) {
+	testcases := []struct {
+		name     string
+		files    []os.FileInfo
+		includes []string
+		excludes []string
+		want     []os.FileInfo
+		wantErr  bool
+	}{
+		{
+			name: "both includes and excludes aren't given",
+			files: []os.FileInfo{
+				&fakeFileInfo{
+					name: "file-1",
+				},
+			},
+			want: []os.FileInfo{
+				&fakeFileInfo{
+					name: "file-1",
+				},
+			},
+			wantErr: false,
+		},
+		{
+			name: "both includes and excludes are given",
+			files: []os.FileInfo{
+				&fakeFileInfo{
+					name: "file-1",
+				},
+			},
+			want:     []os.FileInfo{},
+			includes: []string{"file-1"},
+			excludes: []string{"file-1"},
+			wantErr:  false,
+		},
+		{
+			name: "includes given",
+			files: []os.FileInfo{
+				&fakeFileInfo{
+					name: "file-1",
+				},
+				&fakeFileInfo{
+					name: "file-2",
+				},
+				&fakeFileInfo{
+					name: "file-3",
+				},
+			},
+			includes: []string{"file-1", "file-3"},
+			want: []os.FileInfo{
+				&fakeFileInfo{
+					name: "file-1",
+				},
+				&fakeFileInfo{
+					name: "file-3",
+				},
+			},
+			wantErr: false,
+		},
+		{
+			name: "excludes given",
+			files: []os.FileInfo{
+				&fakeFileInfo{
+					name: "file-1",
+				},
+				&fakeFileInfo{
+					name: "file-2",
+				},
+				&fakeFileInfo{
+					name: "file-3",
+				},
+			},
+			excludes: []string{"file-1", "file-3"},
+			want: []os.FileInfo{
+				&fakeFileInfo{
+					name: "file-2",
+				},
+			},
+			wantErr: false,
+		},
+	}
+	for _, tc := range testcases {
+		t.Run(tc.name, func(t *testing.T) {
+			got, err := filterEventWatcherFiles(tc.files, tc.includes, tc.excludes)
+			assert.Equal(t, tc.wantErr, err != nil)
+			assert.Equal(t, tc.want, got)
+		})
+	}
+}
diff --git a/pkg/config/image_watcher_test.go b/pkg/config/image_watcher_test.go
index 44258ed241..7698e3c2b3 100644
--- a/pkg/config/image_watcher_test.go
+++ b/pkg/config/image_watcher_test.go
@@ -17,24 +17,10 @@ package config
 import (
 	"os"
 	"testing"
-	"time"
 
 	"github.com/stretchr/testify/assert"
 )
 
-type fakeFileInfo struct {
-	name string
-}
-
-func (f *fakeFileInfo) Name() string { return f.name }
-
-// Below methods are required to meet the interface.
-func (f *fakeFileInfo) Size() int64        { return 0 }
-func (f *fakeFileInfo) Mode() os.FileMode  { return 0 }
-func (f *fakeFileInfo) ModTime() time.Time { return time.Now() }
-func (f *fakeFileInfo) IsDir() bool        { return false }
-func (f *fakeFileInfo) Sys() interface{}   { return nil }
-
 func TestFilterImageWatcherFiles(t *testing.T) {
 	testcases := []struct {
 		name     string
diff --git a/pkg/config/piped.go b/pkg/config/piped.go
index 1f39186f6d..2bea4868af 100644
--- a/pkg/config/piped.go
+++ b/pkg/config/piped.go
@@ -61,6 +61,8 @@ type PipedSpec struct {
 	SealedSecretManagement *SealedSecretManagement `json:"sealedSecretManagement"`
 	// Optional settings for image watcher.
 	ImageWatcher PipedImageWatcher `json:"imageWatcher"`
+	// Optional settings for event watcher.
+	EventWatcher PipedEventWatcher `json:"eventWatcher"`
 }
 
 // Validate validates configured data of all fields.
@@ -641,3 +643,40 @@ type PipedImageWatcherGitRepo struct {
 	// This is prioritized if both includes and this are given.
 	Excludes []string `json:"excludes"`
 }
+
+type PipedEventWatcher struct {
+	// Interval to fetch the latest event and compare it with one defined in EventWatcher config files
+	CheckInterval Duration `json:"checkInterval"`
+	// Settings for each git repository.
+	GitRepos []PipedEventWatcherGitRepo `json:"gitRepos"`
+}
+
+func (p *PipedEventWatcher) Validate() error {
+	seen := make(map[string]struct{}, len(p.GitRepos))
+	for i, repo := range p.GitRepos {
+		// Validate the existence of repo ID.
+		if repo.RepoID == "" {
+			return fmt.Errorf("missing repoID at index %d", i)
+		}
+		// Validate if duplicated repository settings exist.
+		if _, ok := seen[repo.RepoID]; ok {
+			return fmt.Errorf("duplicated repo id (%s) found in the eventWatcher directive", repo.RepoID)
+		}
+		seen[repo.RepoID] = struct{}{}
+	}
+	return nil
+}
+
+type PipedEventWatcherGitRepo struct {
+	// Id of the git repository. This must be unique within
+	// the repos' elements.
+	RepoID string `json:"repoId"`
+	// The commit message used to push after replacing values.
+	// Default message is used if not given.
+	CommitMessage string `json:"commitMessage"`
+	// The paths to files to be included.
+	Includes []string `json:"includes"`
+	// The paths to files to be excluded.
+	// This is prioritized if both includes and this one are given.
+	Excludes []string `json:"excludes"`
+}
diff --git a/pkg/config/piped_test.go b/pkg/config/piped_test.go
index 328014ef80..d22088c9d5 100644
--- a/pkg/config/piped_test.go
+++ b/pkg/config/piped_test.go
@@ -231,6 +231,16 @@ func TestPipedConfig(t *testing.T) {
 						},
 					},
 				},
+				EventWatcher: PipedEventWatcher{
+					CheckInterval: Duration(10 * time.Minute),
+					GitRepos: []PipedEventWatcherGitRepo{
+						{
+							RepoID:        "repo-1",
+							CommitMessage: "Update values by Event watcher",
+							Includes:      []string{"event-watcher-dev.yaml", "event-watcher-stg.yaml"},
+						},
+					},
+				},
 			},
 			expectedError: nil,
 		},
diff --git a/pkg/config/testdata/.pipe/event-watcher.yaml b/pkg/config/testdata/.pipe/event-watcher.yaml
new file mode 100644
index 0000000000..fdbe3fd5fe
--- /dev/null
+++ b/pkg/config/testdata/.pipe/event-watcher.yaml
@@ -0,0 +1,14 @@
+apiVersion: pipecd.dev/v1beta1
+kind: EventWatcher
+spec:
+  events:
+    - name: app1-image-update
+      replacements:
+        - file: app1/deployment.yaml
+          yamlField: $.spec.template.spec.containers[0].image
+    - name: app2-helm-release
+      labels:
+        repoId: repo-1
+      replacements:
+        - file: app2/.pipe.yaml
+          yamlField: $.spec.input.helmChart.version
diff --git a/pkg/config/testdata/piped/piped-config.yaml b/pkg/config/testdata/piped/piped-config.yaml
index ca83a7f222..07cb7b319e 100644
--- a/pkg/config/testdata/piped/piped-config.yaml
+++ b/pkg/config/testdata/piped/piped-config.yaml
@@ -140,3 +140,12 @@ spec:
         includes:
           - imagewatcher-dev.yaml
           - imagewatcher-stg.yaml
+
+  eventWatcher:
+    checkInterval: 10m
+    gitRepos:
+      - repoId: repo-1
+        commitMessage: Update values by Event watcher
+        includes:
+          - event-watcher-dev.yaml
+          - event-watcher-stg.yaml