diff --git a/trl/experimental/gold/gold_trainer.py b/trl/experimental/gold/gold_trainer.py
index b2697d94623..635ee417de5 100644
--- a/trl/experimental/gold/gold_trainer.py
+++ b/trl/experimental/gold/gold_trainer.py
@@ -29,7 +29,7 @@
 from accelerate.utils import DistributedType, broadcast_object_list, gather_object, is_peft_model
 from datasets import Dataset, IterableDataset
 from torch.distributed.fsdp import FullyShardedDataParallel as FSDP
-from transformers import AutoTokenizer
+from transformers import AutoTokenizer, is_bitsandbytes_available
 from transformers.data.data_collator import DataCollator
 from transformers.feature_extraction_utils import FeatureExtractionMixin
 from transformers.generation.configuration_utils import GenerationConfig
@@ -84,6 +84,9 @@
     from rich.table import Table
     from rich.text import Text
 
+if is_bitsandbytes_available():
+    import bitsandbytes as bnb
+
 
 def print_prompt_completions_sample_uld(
     prompts: list[str],
@@ -941,6 +944,15 @@ def __init__(
                 os.environ["WORLD_SIZE"] = str(self.accelerator.num_processes)
                 ensure_master_addr_port()
 
+                vllm_quantization = None
+                if is_bitsandbytes_available():
+                    for _, module in model.named_modules():
+                        if isinstance(module, bnb.nn.Linear4bit):
+                            vllm_quantization = "bitsandbytes"
+                            break
+                        elif isinstance(module, bnb.nn.Linear8bitLt):
+                            raise ValueError("vLLM does not support in-flight 8-bit quantization.")
+
                 self.vllm_engine = LLM(
                     model=student_model_name_or_path,
                     revision=self.model_revision,
@@ -952,6 +964,7 @@ def __init__(
                     # Feed identical seed for tp groups to ensure sampling results are the same across workers
                     seed=self.accelerator.process_index // self.vllm_tensor_parallel_size,
                     enable_sleep_mode=self.vllm_enable_sleep_mode,
+                    quantization=vllm_quantization,
                 )
 
                 if self.vllm_enable_sleep_mode:
diff --git a/trl/scripts/grpo.py b/trl/scripts/grpo.py
index 7e46a3858fc..ece0ae55808 100644
--- a/trl/scripts/grpo.py
+++ b/trl/scripts/grpo.py
@@ -27,6 +27,7 @@
 import sys
 from dataclasses import dataclass, field
 
+import torch
 from accelerate import logging
 from datasets import load_dataset
 
@@ -38,7 +39,9 @@
     ScriptArguments,
     TrlParser,
     get_dataset,
+    get_kbit_device_map,
     get_peft_config,
+    get_quantization_config,
 )
 from trl.rewards import accuracy_reward, get_soft_overlong_punishment, think_format_reward
 
@@ -112,6 +115,21 @@ def main(script_args, training_args, model_args, dataset_args):
                     f"Could not load reward function '{func_name}'. Expected one of "
                     f"{list(reward_funcs_registry.keys())} or a valid import path."
                 )
+    dtype = model_args.dtype if model_args.dtype in ["auto", None] else getattr(torch, model_args.dtype)
+
+    model_kwargs = dict(
+        revision=model_args.model_revision,
+        attn_implementation=model_args.attn_implementation,
+        dtype=dtype,
+    )
+    quantization_config = get_quantization_config(model_args)
+
+    if quantization_config is not None:
+        # Passing None would not be treated the same as omitting the argument, so we include it only when valid.
+        model_kwargs["device_map"] = get_kbit_device_map()
+        model_kwargs["quantization_config"] = quantization_config
+
+    training_args.model_init_kwargs = model_kwargs
 
     # Load the dataset
     if dataset_args.datasets and script_args.dataset_name:
diff --git a/trl/trainer/grpo_trainer.py b/trl/trainer/grpo_trainer.py
index b2517eb7903..3343f716c81 100644
--- a/trl/trainer/grpo_trainer.py
+++ b/trl/trainer/grpo_trainer.py
@@ -45,6 +45,7 @@
     PreTrainedTokenizerBase,
     ProcessorMixin,
     TrainerCallback,
+    is_bitsandbytes_available,
     is_trackio_available,
     is_wandb_available,
 )
@@ -101,6 +102,8 @@
 if is_trackio_available():
     import trackio
 
+if is_bitsandbytes_available():
+    import bitsandbytes as bnb
 
 logger = logging.get_logger(__name__)
 
@@ -596,6 +599,15 @@ def cast_outputs_to_original_dtype(module, args, output):
                     max_model_len = self.max_prompt_length + self.max_completion_length
                 else:
                     max_model_len = None
+
+                vllm_quantization = None
+                if is_bitsandbytes_available():
+                    for _, module in model.named_modules():
+                        if isinstance(module, bnb.nn.Linear4bit):
+                            vllm_quantization = "bitsandbytes"
+                            break
+                        elif isinstance(module, bnb.nn.Linear8bitLt):
+                            raise ValueError("vLLM does not support in-flight 8-bit quantization.")
                 self.llm = LLM(
                     model=model.name_or_path,
                     tensor_parallel_size=args.vllm_tensor_parallel_size,
@@ -613,6 +625,7 @@ def cast_outputs_to_original_dtype(module, args, output):
                     enable_sleep_mode=self.args.vllm_enable_sleep_mode,
                     # Important so temperature scaling/logit tweaking affects the TIS log probs
                     logprobs_mode="processed_logprobs",
+                    quantization=vllm_quantization,
                 )
                 if self.args.vllm_enable_sleep_mode:
                     self.llm.sleep(level=2)
diff --git a/trl/trainer/model_config.py b/trl/trainer/model_config.py
index a7556b47646..84bb1450b6a 100644
--- a/trl/trainer/model_config.py
+++ b/trl/trainer/model_config.py
@@ -176,6 +176,10 @@ class ModelConfig:
         default=False,
         metadata={"help": "Whether to use nested quantization."},
     )
+    bnb_4bit_quant_storage: str | None = field(
+        default=None,
+        metadata={"help": "Quantization storage dtype"},
+    )
     # Deprecated params
     torch_dtype: str | None = field(
         default=None,
diff --git a/trl/trainer/online_dpo_trainer.py b/trl/trainer/online_dpo_trainer.py
index cdbd5458fe8..1b4e487c861 100644
--- a/trl/trainer/online_dpo_trainer.py
+++ b/trl/trainer/online_dpo_trainer.py
@@ -45,6 +45,7 @@
     ProcessorMixin,
     Trainer,
     TrainerCallback,
+    is_bitsandbytes_available,
 )
 from transformers.models.auto.modeling_auto import MODEL_FOR_IMAGE_TEXT_TO_TEXT_MAPPING_NAMES
 from transformers.trainer_utils import EvalPrediction, seed_worker
@@ -97,6 +98,8 @@
     from vllm import LLM, SamplingParams
     from vllm.sampling_params import GuidedDecodingParams
 
+if is_bitsandbytes_available():
+    import bitsandbytes as bnb
 
 logger = logging.get_logger(__name__)
 
@@ -477,6 +480,14 @@ def __init__(
                 # after the first optimizer step and remain in GPU memory throughout training. So we must reserve enough
                 # space for them.
                 # Configure vLLM parameters
+                vllm_quantization = None
+                if is_bitsandbytes_available():
+                    for _, module in model.named_modules():
+                        if isinstance(module, bnb.nn.Linear4bit):
+                            vllm_quantization = "bitsandbytes"
+                            break
+                        elif isinstance(module, bnb.nn.Linear8bitLt):
+                            raise ValueError("vLLM does not support in-flight 8-bit quantization.")
                 vllm_kwargs = {
                     "model": model.name_or_path,
                     "tensor_parallel_size": self.vllm_tensor_parallel_size,
@@ -489,6 +500,7 @@ def __init__(
                     "seed": self.accelerator.process_index // self.vllm_tensor_parallel_size,
                     # Latest vLLM v1 memory profiler is misled by the high default value (i.e., 32768)
                     "max_num_batched_tokens": 4096,
+                    "quantization": vllm_quantization,
                 }
 
                 # vLLM requires the environment variables to be set for distributed training.
diff --git a/trl/trainer/rloo_trainer.py b/trl/trainer/rloo_trainer.py
index 2ee731dbd65..ca572caae7e 100644
--- a/trl/trainer/rloo_trainer.py
+++ b/trl/trainer/rloo_trainer.py
@@ -45,6 +45,7 @@
     PreTrainedTokenizerBase,
     ProcessorMixin,
     TrainerCallback,
+    is_bitsandbytes_available,
     is_trackio_available,
     is_wandb_available,
 )
@@ -97,6 +98,9 @@
 if is_trackio_available():
     import trackio
 
+if is_bitsandbytes_available():
+    import bitsandbytes as bnb
+
 
 logger = logging.get_logger(__name__)
 
@@ -513,6 +517,14 @@ def __init__(
                     max_model_len = self.max_prompt_length + self.max_completion_length
                 else:
                     max_model_len = None
+                vllm_quantization = None
+                if is_bitsandbytes_available():
+                    for _, module in model.named_modules():
+                        if isinstance(module, bnb.nn.Linear4bit):
+                            vllm_quantization = "bitsandbytes"
+                            break
+                        elif isinstance(module, bnb.nn.Linear8bitLt):
+                            raise ValueError("vLLM does not support in-flight 8-bit quantization.")
                 self.llm = LLM(
                     model=model.name_or_path,
                     tensor_parallel_size=args.vllm_tensor_parallel_size,
@@ -528,6 +540,7 @@ def __init__(
                     max_num_batched_tokens=4096,
                     model_impl=self.args.vllm_model_impl,
                     enable_sleep_mode=self.args.vllm_enable_sleep_mode,
+                    quantization=vllm_quantization,
                 )
                 if self.args.vllm_enable_sleep_mode:
                     self.llm.sleep(level=2)
diff --git a/trl/trainer/utils.py b/trl/trainer/utils.py
index 529c6bb622a..02d4cc78073 100644
--- a/trl/trainer/utils.py
+++ b/trl/trainer/utils.py
@@ -662,7 +662,7 @@ def get_quantization_config(model_args: ModelConfig) -> BitsAndBytesConfig | Non
             bnb_4bit_compute_dtype=model_args.dtype,  # For consistency with model weights, we use the same value as `dtype`
             bnb_4bit_quant_type=model_args.bnb_4bit_quant_type,
             bnb_4bit_use_double_quant=model_args.use_bnb_nested_quant,
-            bnb_4bit_quant_storage=model_args.dtype,
+            bnb_4bit_quant_storage=model_args.bnb_4bit_quant_storage,
         )
     elif model_args.load_in_8bit:
         quantization_config = BitsAndBytesConfig(