diff --git a/.circleci/config.yml b/.circleci/config.yml
index 758d62b53e956..1649da56d2f5b 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -1422,6 +1422,19 @@ jobs:
           paths:
             - "/home/circleci/.cache/golangci-lint"
 
+  check-op-geth-version:
+    docker:
+      - image: <<pipeline.parameters.default_docker_image>>
+    resource_class: small
+    steps:
+      - utils/checkout-with-mise:
+          checkout-method: blobless
+          enable-mise-cache: true
+      - run:
+          name: check op-geth version
+          command: |
+            make check-op-geth-version
+
   go-tests:
     parameters:
       notify:
@@ -2824,6 +2837,9 @@ workflows:
       - go-lint:
           context:
             - circleci-repo-readonly-authenticated-github-token
+      - check-op-geth-version:
+          context:
+            - circleci-repo-readonly-authenticated-github-token
       - fuzz-golang:
           name: fuzz-golang-<<matrix.package_name>>
           on_changes: <<matrix.package_name>>
diff --git a/Makefile b/Makefile
index a0ada6a77d8a9..403f0e7a3f407 100644
--- a/Makefile
+++ b/Makefile
@@ -29,6 +29,10 @@ lint-go-fix: ## Lints Go code with specific linters and fixes reported issues
 	golangci-lint run ./... --fix
 .PHONY: lint-go-fix
 
+check-op-geth-version: ## Checks that op-geth version in go.mod is valid
+	go run ./ops/scripts/check-op-geth-version
+.PHONY: check-op-geth-version
+
 golang-docker: ## Builds Docker images for Go components using buildx
 	# We don't use a buildx builder here, and just load directly into regular docker, for convenience.
 	GIT_COMMIT=$$(git rev-parse HEAD) \
diff --git a/op-service/util.go b/op-service/util.go
index 84d8e0d864c40..0c0ec79e09d1a 100644
--- a/op-service/util.go
+++ b/op-service/util.go
@@ -13,6 +13,7 @@ import (
 	"time"
 
 	"github.com/ethereum/go-ethereum/common/hexutil"
+	"golang.org/x/mod/modfile"
 
 	"github.com/ethereum-optimism/optimism/op-service/ctxinterrupt"
 
@@ -115,17 +116,23 @@ func CloseAction(ctx context.Context, fn func(ctx context.Context) error) error
 	}
 }
 
-// FindMonorepoRoot will recursively search upwards for a go.mod file.
-// This depends on the structure of the monorepo having a go.mod file at the root.
+// FindMonorepoRoot will recursively search upwards for the monorepo's go.mod file.
+// It verifies that the go.mod file belongs to the optimism monorepo by checking the module path.
 func FindMonorepoRoot(startDir string) (string, error) {
 	dir, err := filepath.Abs(startDir)
 	if err != nil {
 		return "", err
 	}
 	for {
-		modulePath := filepath.Join(dir, "go.mod")
-		if _, err := os.Stat(modulePath); err == nil {
-			return dir, nil
+		goModPath := filepath.Join(dir, "go.mod")
+		if content, err := os.ReadFile(goModPath); err == nil {
+			modFile, err := modfile.Parse(goModPath, content, nil)
+			if err != nil {
+				return "", fmt.Errorf("parsing go.mod: %w", err)
+			}
+			if modFile.Module.Mod.Path == "github.com/ethereum-optimism/optimism" {
+				return dir, nil
+			}
 		}
 		parentDir := filepath.Dir(dir)
 		// Check if we reached the filesystem root
diff --git a/ops/scripts/check-op-geth-version/main.go b/ops/scripts/check-op-geth-version/main.go
new file mode 100644
index 0000000000000..6e253762ad401
--- /dev/null
+++ b/ops/scripts/check-op-geth-version/main.go
@@ -0,0 +1,74 @@
+package main
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+	"regexp"
+
+	"golang.org/x/mod/modfile"
+
+	opservice "github.com/ethereum-optimism/optimism/op-service"
+)
+
+const (
+	goEthereumPath = "github.com/ethereum/go-ethereum"
+	opGethPath     = "github.com/ethereum-optimism/op-geth"
+)
+
+// The op-geth minor version encodes the upstream geth version as exactly 6 digits:
+//   - 2 digits for geth major version (zero-padded)
+//   - 2 digits for geth minor version (zero-padded)
+//   - 2 digits for geth patch version (zero-padded)
+//
+// Examples:
+//   - v1.101407.0      -> geth v1.14.7
+//   - v1.101605.0-rc.2 -> geth v1.16.5
+var opGethVersionPattern = regexp.MustCompile(`^v\d+\.\d{6}\.\d+(-rc\.\d+)?$`)
+
+func main() {
+	if err := run("."); err != nil {
+		fmt.Fprintf(os.Stderr, "error: %v\n", err)
+		os.Exit(1)
+	}
+}
+
+func run(dir string) error {
+	root, err := opservice.FindMonorepoRoot(dir)
+	if err != nil {
+		return fmt.Errorf("finding monorepo root: %w", err)
+	}
+
+	goModPath := filepath.Join(root, "go.mod")
+	content, err := os.ReadFile(goModPath)
+	if err != nil {
+		return fmt.Errorf("reading go.mod: %w", err)
+	}
+
+	modFile, err := modfile.Parse(goModPath, content, nil)
+	if err != nil {
+		return fmt.Errorf("parsing go.mod: %w", err)
+	}
+
+	// Find the replace directive for go-ethereum -> op-geth
+	var opGethVersion string
+	for _, rep := range modFile.Replace {
+		if rep.Old.Path == goEthereumPath {
+			if rep.New.Path != opGethPath {
+				return fmt.Errorf("go-ethereum replacement must point to %s, got %s", opGethPath, rep.New.Path)
+			}
+			opGethVersion = rep.New.Version
+			break
+		}
+	}
+
+	if opGethVersion == "" {
+		return fmt.Errorf("no replace directive found for %s", goEthereumPath)
+	}
+
+	if !opGethVersionPattern.MatchString(opGethVersion) {
+		return fmt.Errorf("invalid op-geth version %q", opGethVersion)
+	}
+
+	return nil
+}
diff --git a/ops/scripts/check-op-geth-version/main_test.go b/ops/scripts/check-op-geth-version/main_test.go
new file mode 100644
index 0000000000000..de4b25115401e
--- /dev/null
+++ b/ops/scripts/check-op-geth-version/main_test.go
@@ -0,0 +1,31 @@
+package main
+
+import (
+	"path/filepath"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestRun(t *testing.T) {
+	tests := map[string]string{
+		"valid":                 "",
+		"valid-rc":              "",
+		"invalid-version":       "invalid op-geth version",
+		"invalid-geth-encoding": "invalid op-geth version",
+		"wrong-replacement":     "must point to github.com/ethereum-optimism/op-geth",
+		"no-replacement":        "no replace directive found",
+	}
+	for name, errContains := range tests {
+		t.Run(name, func(t *testing.T) {
+			testDir, err := filepath.Abs(filepath.Join("testdata", name))
+			require.NoError(t, err)
+			if err = run(testDir); errContains == "" {
+				require.NoError(t, err)
+			} else {
+				require.Error(t, err)
+				require.ErrorContains(t, err, errContains)
+			}
+		})
+	}
+}
diff --git a/ops/scripts/check-op-geth-version/testdata/invalid-geth-encoding/go.mod b/ops/scripts/check-op-geth-version/testdata/invalid-geth-encoding/go.mod
new file mode 100644
index 0000000000000..0967eda22dda0
--- /dev/null
+++ b/ops/scripts/check-op-geth-version/testdata/invalid-geth-encoding/go.mod
@@ -0,0 +1,5 @@
+module github.com/ethereum-optimism/optimism
+
+go 1.22.0
+
+replace github.com/ethereum/go-ethereum => github.com/ethereum-optimism/op-geth v1.11407.0
diff --git a/ops/scripts/check-op-geth-version/testdata/invalid-version/go.mod b/ops/scripts/check-op-geth-version/testdata/invalid-version/go.mod
new file mode 100644
index 0000000000000..53c3f6cc6cfa0
--- /dev/null
+++ b/ops/scripts/check-op-geth-version/testdata/invalid-version/go.mod
@@ -0,0 +1,5 @@
+module github.com/ethereum-optimism/optimism
+
+go 1.22.0
+
+replace github.com/ethereum/go-ethereum => github.com/ethereum-optimism/op-geth v1.101605.0-beta.1
diff --git a/ops/scripts/check-op-geth-version/testdata/no-replacement/go.mod b/ops/scripts/check-op-geth-version/testdata/no-replacement/go.mod
new file mode 100644
index 0000000000000..e4ccc4695c4ed
--- /dev/null
+++ b/ops/scripts/check-op-geth-version/testdata/no-replacement/go.mod
@@ -0,0 +1,3 @@
+module github.com/ethereum-optimism/optimism
+
+go 1.22.0
diff --git a/ops/scripts/check-op-geth-version/testdata/pseudoversion/go.mod b/ops/scripts/check-op-geth-version/testdata/pseudoversion/go.mod
new file mode 100644
index 0000000000000..9edbf55c6a6b6
--- /dev/null
+++ b/ops/scripts/check-op-geth-version/testdata/pseudoversion/go.mod
@@ -0,0 +1,5 @@
+module github.com/ethereum-optimism/optimism
+
+go 1.22.0
+
+replace github.com/ethereum/go-ethereum => github.com/ethereum-optimism/op-geth v1.101605.1-0.20260113212524-7f3b615ab10d
diff --git a/ops/scripts/check-op-geth-version/testdata/valid-rc/go.mod b/ops/scripts/check-op-geth-version/testdata/valid-rc/go.mod
new file mode 100644
index 0000000000000..b75fce3ea7cbe
--- /dev/null
+++ b/ops/scripts/check-op-geth-version/testdata/valid-rc/go.mod
@@ -0,0 +1,5 @@
+module github.com/ethereum-optimism/optimism
+
+go 1.22.0
+
+replace github.com/ethereum/go-ethereum => github.com/ethereum-optimism/op-geth v1.101605.0-rc.2
diff --git a/ops/scripts/check-op-geth-version/testdata/valid/go.mod b/ops/scripts/check-op-geth-version/testdata/valid/go.mod
new file mode 100644
index 0000000000000..5b4abab3f0c4f
--- /dev/null
+++ b/ops/scripts/check-op-geth-version/testdata/valid/go.mod
@@ -0,0 +1,5 @@
+module github.com/ethereum-optimism/optimism
+
+go 1.22.0
+
+replace github.com/ethereum/go-ethereum => github.com/ethereum-optimism/op-geth v1.101605.0
diff --git a/ops/scripts/check-op-geth-version/testdata/wrong-replacement/go.mod b/ops/scripts/check-op-geth-version/testdata/wrong-replacement/go.mod
new file mode 100644
index 0000000000000..ffd3752f63314
--- /dev/null
+++ b/ops/scripts/check-op-geth-version/testdata/wrong-replacement/go.mod
@@ -0,0 +1,5 @@
+module github.com/ethereum-optimism/optimism
+
+go 1.22.0
+
+replace github.com/ethereum/go-ethereum => github.com/some-other/fork v1.0.0