diff --git a/vllm/model_executor/models/gemma3n.py b/vllm/model_executor/models/gemma3n.py
index a58b32793dbe..e16c03c8d3b5 100644
--- a/vllm/model_executor/models/gemma3n.py
+++ b/vllm/model_executor/models/gemma3n.py
@@ -46,6 +46,7 @@ from vllm.model_executor.model_loader.weight_utils import (
 from vllm.model_executor.sampling_metadata import SamplingMetadata
 from vllm.sequence import IntermediateTensors
 
+from .interfaces import SupportsQuant
 from .utils import (AutoWeightsLoader, extract_layer_index,
                     is_pp_missing_parameter, make_layers, maybe_prefix)
 
@@ -68,6 +69,7 @@ class Gemma3nAltUp(nn.Module):
         altup_num_inputs: int,
         altup_coef_clip: float,
         altup_active_idx: int,
+        quant_config: QuantizationConfig,
         prefix: str,
     ):
         super().__init__()
@@ -80,6 +82,7 @@ class Gemma3nAltUp(nn.Module):
             altup_num_inputs,
             altup_num_inputs,
             bias=False,
+            quant_config=quant_config,
             prefix=f"{prefix}.correction_coefs",
             return_bias=False,
         )
@@ -87,6 +90,7 @@ class Gemma3nAltUp(nn.Module):
             altup_num_inputs,
             altup_num_inputs**2,
             bias=False,
+            quant_config=quant_config,
             prefix=f"{prefix}.prediction_coefs",
             return_bias=False,
         )
@@ -94,6 +98,7 @@ class Gemma3nAltUp(nn.Module):
             hidden_size,
             altup_num_inputs,
             bias=False,
+            quant_config=quant_config,
             prefix=f"{prefix}.modality_router",
             return_bias=False,
         )
@@ -400,6 +405,7 @@ class Gemma3nDecoderLayer(nn.Module):
             altup_num_inputs=config.altup_num_inputs,
             altup_coef_clip=config.altup_coef_clip,
             altup_active_idx=config.altup_active_idx,
+            quant_config=quant_config,
             prefix=f"{prefix}.altup",
         )
         self.self_attn = Gemma3nAttention(
@@ -527,7 +533,7 @@ class Gemma3nDecoderLayer(nn.Module):
 
 
 @support_torch_compile
-class Gemma3nTextModel(nn.Module):
+class Gemma3nTextModel(nn.Module, SupportsQuant):
 
     def __init__(self, *, vllm_config: VllmConfig, prefix: str = ""):
         super().__init__()
@@ -540,6 +546,7 @@ class Gemma3nTextModel(nn.Module):
         self.embed_tokens = VocabParallelEmbedding(
             config.vocab_size,
             config.hidden_size,
+            quant_config=quant_config,
             prefix=f"{prefix}.embed_tokens",
         )
         self.embed_scale = torch.tensor(
@@ -549,6 +556,7 @@ class Gemma3nTextModel(nn.Module):
         self.embed_tokens_per_layer = VocabParallelEmbedding(
             config.vocab_size_per_layer_input,
             config.num_hidden_layers * config.hidden_size_per_layer_input,
+            quant_config=quant_config,
             prefix=f"{prefix}.per_layer_embed_tokens",
         )
         self.embed_scale_per_layer = torch.tensor(
@@ -582,7 +590,7 @@ class Gemma3nTextModel(nn.Module):
                 gather_output=True,
                 return_bias=False,
                 quant_config=quant_config,
-                prefix=f"{prefix}.{idx-1}.altup_projections",
+                prefix=f"{prefix}.altup_projections.{idx-1}",
             ) for idx in range(1, self.config.altup_num_inputs)
         ])
         self.altup_unembed_projections = nn.ModuleList([
@@ -593,7 +601,7 @@ class Gemma3nTextModel(nn.Module):
                 gather_output=True,
                 return_bias=False,
                 quant_config=quant_config,
-                prefix=f"{prefix}.{idx-1}.altup_unembed_projections",
+                prefix=f"{prefix}.altup_unembed_projections.{idx-1}",
             ) for idx in range(1, self.config.altup_num_inputs)
         ])
 
@@ -774,7 +782,7 @@ class Gemma3nModel(nn.Module):
                                    **kwargs)
 
 
-class Gemma3nForConditionalGeneration(nn.Module):
+class Gemma3nForConditionalGeneration(nn.Module, SupportsQuant):
     packed_modules_mapping = {
         "qkv_proj": [
             "q_proj",