diff --git a/changelog/3696.added.md b/changelog/3696.added.md
new file mode 100644
index 000000000..39726d930
--- /dev/null
+++ b/changelog/3696.added.md
@@ -0,0 +1 @@
+- Added `TextAggregationMetricsData` metric measuring the time from the first LLM token to the first complete sentence, representing the latency cost of sentence aggregation in the TTS pipeline.
diff --git a/src/pipecat/metrics/metrics.py b/src/pipecat/metrics/metrics.py
index ccf30227a..2030306e5 100644
--- a/src/pipecat/metrics/metrics.py
+++ b/src/pipecat/metrics/metrics.py
@@ -87,6 +87,19 @@ class TTSUsageMetricsData(MetricsData):
     value: int
 
 
+class TextAggregationMetricsData(MetricsData):
+    """Text aggregation time metrics data.
+
+    Measures the time from the first LLM token to the first complete sentence,
+    representing the latency cost of sentence aggregation in the TTS pipeline.
+
+    Parameters:
+        value: Aggregation time in seconds.
+    """
+
+    value: float
+
+
 class TurnMetricsData(MetricsData):
     """Metrics data for turn detection predictions.
 
diff --git a/src/pipecat/processors/frame_processor.py b/src/pipecat/processors/frame_processor.py
index bcdb2d57b..37e8dc10d 100644
--- a/src/pipecat/processors/frame_processor.py
+++ b/src/pipecat/processors/frame_processor.py
@@ -485,6 +485,18 @@ class FrameProcessor(BaseObject):
             if frame:
                 await self.push_frame(frame)
 
+    async def start_text_aggregation_metrics(self):
+        """Start text aggregation time metrics collection."""
+        if self.can_generate_metrics() and self.metrics_enabled:
+            await self._metrics.start_text_aggregation_metrics()
+
+    async def stop_text_aggregation_metrics(self):
+        """Stop text aggregation time metrics collection and push results."""
+        if self.can_generate_metrics() and self.metrics_enabled:
+            frame = await self._metrics.stop_text_aggregation_metrics()
+            if frame:
+                await self.push_frame(frame)
+
     async def stop_all_metrics(self):
         """Stop all active metrics collection."""
         await self.stop_ttfb_metrics()
diff --git a/src/pipecat/processors/metrics/frame_processor_metrics.py b/src/pipecat/processors/metrics/frame_processor_metrics.py
index c82fd9698..cb5bc8a42 100644
--- a/src/pipecat/processors/metrics/frame_processor_metrics.py
+++ b/src/pipecat/processors/metrics/frame_processor_metrics.py
@@ -17,6 +17,7 @@ from pipecat.metrics.metrics import (
     LLMUsageMetricsData,
     MetricsData,
     ProcessingMetricsData,
+    TextAggregationMetricsData,
     TTFBMetricsData,
     TTSUsageMetricsData,
 )
@@ -211,3 +212,27 @@ class FrameProcessorMetrics(BaseObject):
         )
         logger.debug(f"{self._processor_name()} usage characters: {characters.value}")
         return MetricsFrame(data=[characters])
+
+    async def start_text_aggregation_metrics(self):
+        """Start measuring text aggregation time (first token to first sentence)."""
+        self._start_text_aggregation_time = time.time()
+
+    async def stop_text_aggregation_metrics(self):
+        """Stop text aggregation measurement and generate metrics frame.
+
+        Returns:
+            MetricsFrame containing text aggregation time, or None if not measuring.
+        """
+        if (
+            not hasattr(self, "_start_text_aggregation_time")
+            or self._start_text_aggregation_time == 0
+        ):
+            return None
+
+        value = time.time() - self._start_text_aggregation_time
+        logger.debug(f"{self._processor_name()} text aggregation time: {value}")
+        aggregation = TextAggregationMetricsData(
+            processor=self._processor_name(), value=value, model=self._model_name()
+        )
+        self._start_text_aggregation_time = 0
+        return MetricsFrame(data=[aggregation])