diff --git a/tests/unit/vertexai/genai/test_evals.py b/tests/unit/vertexai/genai/test_evals.py
index ec6c50a456..a9b62bebfe 100644
--- a/tests/unit/vertexai/genai/test_evals.py
+++ b/tests/unit/vertexai/genai/test_evals.py
@@ -13,9 +13,11 @@
 # limitations under the License.
 #
 # pylint: disable=protected-access,bad-continuation,
+import base64
 import importlib
 import json
 import os
+import re
 import statistics
 import sys
 from unittest import mock
@@ -291,8 +293,72 @@ def test_display_evaluation_result_with_agent_trace_prefixes(self, mock_is_ipyth
 
         mock_display_module.HTML.assert_called_once()
         html_content = mock_display_module.HTML.call_args[0][0]
-        assert "my_function" in html_content
-        assert "this is model response" in html_content
+        match = re.search(r'atob\("([^"]+)"\)', html_content)
+        assert match
+        decoded_json = base64.b64decode(match.group(1)).decode("utf-8")
+        assert "my_function" in decoded_json
+        assert "this is model response" in decoded_json
+
+        del sys.modules["IPython"]
+        del sys.modules["IPython.display"]
+
+    @mock.patch(
+        "vertexai._genai._evals_visualization._is_ipython_env",
+        return_value=True,
+    )
+    def test_display_evaluation_result_with_non_ascii_character(self, mock_is_ipython):
+        """Tests that non-ASCII characters are handled correctly."""
+        mock_display_module = mock.MagicMock()
+        mock_ipython_module = mock.MagicMock()
+        mock_ipython_module.display = mock_display_module
+        sys.modules["IPython"] = mock_ipython_module
+        sys.modules["IPython.display"] = mock_display_module
+
+        dataset_df = pd.DataFrame(
+            [
+                {
+                    "prompt": "Test prompt with emoji 😊",
+                    "response": "Test response with emoji 😊",
+                },
+            ]
+        )
+        eval_dataset = vertexai_genai_types.EvaluationDataset(
+            eval_dataset_df=dataset_df
+        )
+        eval_result = vertexai_genai_types.EvaluationResult(
+            evaluation_dataset=[eval_dataset],
+            eval_case_results=[
+                vertexai_genai_types.EvalCaseResult(
+                    eval_case_index=0,
+                    response_candidate_results=[
+                        vertexai_genai_types.ResponseCandidateResult(
+                            response_index=0, metric_results={}
+                        )
+                    ],
+                )
+            ],
+        )
+
+        _evals_visualization.display_evaluation_result(eval_result)
+
+        mock_display_module.HTML.assert_called_once()
+        html_content = mock_display_module.HTML.call_args[0][0]
+        # Verify that the new decoding logic is present in the HTML
+        assert "new TextDecoder().decode" in html_content
+
+        match = re.search(r'atob\("([^"]+)"\)', html_content)
+        assert match
+        decoded_json = base64.b64decode(match.group(1)).decode("utf-8")
+
+        # JSON serialization escapes non-ASCII characters (e.g. \uXXXX), so we
+        # parse it back to check for the actual characters.
+        parsed_json = json.loads(decoded_json)
+        assert "Test prompt with emoji 😊" in json.dumps(
+            parsed_json, ensure_ascii=False
+        )
+        assert "Test response with emoji 😊" in json.dumps(
+            parsed_json, ensure_ascii=False
+        )
 
         del sys.modules["IPython"]
         del sys.modules["IPython.display"]
@@ -1290,7 +1356,7 @@ def test_run_inference_with_agent_engine_with_response_column_raises_error(
         ) in str(excinfo.value)
 
     @mock.patch.object(_evals_utils, "EvalDatasetLoader")
-    @mock.patch("vertexai._genai._evals_common.InMemorySessionService")
+    @mock.patch("vertexai._genai._evals_common.InMemorySessionService")  # fmt: skip
     @mock.patch("vertexai._genai._evals_common.Runner")
     @mock.patch("vertexai._genai._evals_common.LlmAgent")
     def test_run_inference_with_local_agent(
diff --git a/vertexai/_genai/_evals_visualization.py b/vertexai/_genai/_evals_visualization.py
index 04012c9394..049f7f95de 100644
--- a/vertexai/_genai/_evals_visualization.py
+++ b/vertexai/_genai/_evals_visualization.py
@@ -14,8 +14,10 @@
 #
 """Visualization utilities for GenAI Evaluation SDK."""
 
+import base64
 import json
 import logging
+import textwrap
 from typing import Any, Optional
 
 import pandas as pd
@@ -78,9 +80,16 @@ def stringify_cell(cell: Any) -> Optional[str]:
     return df_copy
 
 
+def _encode_to_base64(data: str) -> str:
+    """Encodes a string to a web-safe Base64 string."""
+    return base64.b64encode(data.encode("utf-8")).decode("utf-8")
+
+
 def _get_evaluation_html(eval_result_json: str) -> str:
     """Returns a self-contained HTML for single evaluation visualization."""
-    return f"""
+    payload_b64 = _encode_to_base64(eval_result_json)
+    return textwrap.dedent(
+        f"""
 <!DOCTYPE html>
 <html>
 <head>
@@ -249,12 +258,11 @@ def _get_evaluation_html(eval_result_json: str) -> str:
 <body>
     <div class="container">
         <h1>Evaluation Report</h1>
-        <div id="summary-section"></div>
-        <div id="agent-info-section"></div>
-        <div id="details-section"></div>
-    </div>
+        <    <div id="summary-section"></div>
+    <div id="agent-info-section"></div>
+    <div id="details-section"></div>
     <script>
-        var vizData_vertex_eval_sdk = {eval_result_json};
+        var vizData_vertex_eval_sdk = JSON.parse(new TextDecoder().decode(Uint8Array.from(atob("{payload_b64}"), c => c.charCodeAt(0))));
         function formatDictVals(obj) {{
             if (typeof obj === 'string') return obj;
             if (obj === undefined || obj === null) return '';
@@ -552,11 +560,14 @@ def _get_evaluation_html(eval_result_json: str) -> str:
 </body>
 </html>
 """
+    )
 
 
 def _get_comparison_html(eval_result_json: str) -> str:
     """Returns a self-contained HTML for a side-by-side eval comparison."""
-    return f"""
+    payload_b64 = _encode_to_base64(eval_result_json)
+    return textwrap.dedent(
+        f"""
 <!DOCTYPE html>
 <html>
 <head>
@@ -612,11 +623,10 @@ def _get_comparison_html(eval_result_json: str) -> str:
 <body>
     <div class="container">
         <h1>Eval Comparison Report</h1>
-        <div id="summary-section"></div>
-        <div id="details-section"></div>
-    </div>
+        <    <div id="summary-section"></div>
+    <div id="details-section"></div>
     <script>
-        var vizData_vertex_eval_sdk = {eval_result_json};
+        var vizData_vertex_eval_sdk = JSON.parse(new TextDecoder().decode(Uint8Array.from(atob("{payload_b64}"), c => c.charCodeAt(0))));
         function renderSummary(summaryMetrics, metadata) {{
             const container = document.getElementById('summary-section');
             if (!summaryMetrics || summaryMetrics.length === 0) {{ container.innerHTML = '<h2>Summary Metrics</h2><p>No summary metrics.</p>'; return; }}
@@ -692,11 +702,14 @@ def _get_comparison_html(eval_result_json: str) -> str:
 </body>
 </html>
 """
+    )
 
 
 def _get_inference_html(dataframe_json: str) -> str:
     """Returns a self-contained HTML for displaying inference results."""
-    return f"""
+    payload_b64 = _encode_to_base64(dataframe_json)
+    return textwrap.dedent(
+        f"""
 <!DOCTYPE html>
 <html>
 <head>
@@ -741,12 +754,12 @@ def _get_inference_html(dataframe_json: str) -> str:
     </style>
 </head>
 <body>
-    <div class="container">
+    <    <div class="container">
         <h1>Evaluation Dataset</h1>
         <div id="results-table"></div>
     </div>
     <script>
-        var vizData_vertex_eval_sdk = {dataframe_json};
+        var vizData_vertex_eval_sdk = JSON.parse(new TextDecoder().decode(Uint8Array.from(atob("{payload_b64}"), c => c.charCodeAt(0))));
         var container_vertex_eval_sdk = document.getElementById('results-table');
 
         function renderRubrics(cellValue) {{
@@ -822,6 +835,7 @@ def _get_inference_html(dataframe_json: str) -> str:
 </body>
 </html>
 """
+    )
 
 
 def _extract_text_and_raw_json(content: Any) -> dict[str, str]:
@@ -1086,12 +1100,14 @@ def _get_status_html(status: str, error_message: Optional[str] = None) -> str:
         </p>
         """
 
-    return f"""
+    return textwrap.dedent(
+        f"""
     <div>
         <p><b>Status:</b> {status}</p>
         {error_html}
     </div>
     """
+    )
 
 
 def display_evaluation_run_status(eval_run_obj: "types.EvaluationRun") -> None: