diff --git a/singer_sdk/helpers/_flattening.py b/singer_sdk/helpers/_flattening.py
index 9dcbf1281..aef73efc0 100644
--- a/singer_sdk/helpers/_flattening.py
+++ b/singer_sdk/helpers/_flattening.py
@@ -20,6 +20,7 @@ class FlatteningOptions(t.NamedTuple):
     max_level: int
     flattening_enabled: bool = True
     separator: str = DEFAULT_FLATTENING_SEPARATOR
+    nan_strategy: t.Literal["fail", "allow", "convert_null"] = "fail"
 
 
 def get_flattening_options(
@@ -81,6 +82,7 @@ def flatten_schema(
     schema: dict,
     max_level: int,
     separator: str = "__",
+    nan_strategy: t.Literal["fail", "allow", "convert_null"] = "fail",
 ) -> dict:
     """Flatten the provided schema up to a depth of max_level.
 
@@ -88,6 +90,7 @@ def flatten_schema(
         schema: The schema definition to flatten.
         separator: The string to use when concatenating key names.
         max_level: The max recursion level (zero-based, exclusive).
+        nan_strategy: Strategy for handling NaNs in json.
 
     Returns:
         A flattened version of the provided schema definition.
@@ -274,6 +277,7 @@ def flatten_schema(
         schema_node=new_schema,
         max_level=max_level,
         separator=separator,
+        nan_strategy=nan_strategy,
     )
     return new_schema
 
@@ -284,6 +288,7 @@ def _flatten_schema(  # noqa: C901, PLR0912
     separator: str = "__",
     level: int = 0,
     max_level: int = 0,
+    nan_strategy: t.Literal["fail", "allow", "convert_null"] = "fail",
 ) -> dict:
     """Flatten the provided schema node, recursively up to depth of `max_level`.
 
@@ -293,6 +298,7 @@ def _flatten_schema(  # noqa: C901, PLR0912
         separator: The string to use when concatenating key names.
         level: The current recursion level (zero-based).
         max_level: The max recursion level (zero-based, exclusive).
+        nan_strategy: Strategy for handling NaNs in json.
 
     Returns:
         A flattened version of the provided node.
@@ -319,6 +325,7 @@ def _flatten_schema(  # noqa: C901, PLR0912
                         separator=separator,
                         level=level + 1,
                         max_level=max_level,
+                        nan_strategy=nan_strategy,
                     ).items(),
                 )
             elif (
@@ -364,6 +371,7 @@ def flatten_record(
     flattened_schema: dict,
     max_level: int,
     separator: str = "__",
+    nan_strategy: t.Literal["fail", "allow", "convert_null"] = "fail",
 ) -> dict:
     """Flatten a record up to max_level.
 
@@ -372,6 +380,7 @@ def flatten_record(
         flattened_schema: The already flattened schema.
         separator: The string used to separate concatenated key names. Defaults to "__".
         max_level: The maximum depth of keys to flatten recursively.
+        nan_strategy: Strategy for handling NaNs in json.
 
     Returns:
         A flattened version of the record.
@@ -381,6 +390,7 @@ def flatten_record(
         flattened_schema=flattened_schema,
         separator=separator,
         max_level=max_level,
+        nan_strategy=nan_strategy,
     )
 
 
@@ -392,6 +402,7 @@ def _flatten_record(
     separator: str = "__",
     level: int = 0,
     max_level: int = 0,
+    nan_strategy: t.Literal["fail", "allow", "convert_null"] = "fail",
 ) -> dict:
     """This recursive function flattens the record node.
 
@@ -405,6 +416,7 @@ def _flatten_record(
         separator: The string to use when concatenating key names.
         level: The current recursion level (zero-based).
         max_level: The max recursion level (zero-based, exclusive).
+        nan_strategy: Strategy for handling NaNs in json.
 
     Returns:
         A flattened version of the provided node.
@@ -431,13 +443,27 @@ def _flatten_record(
                     separator=separator,
                     level=level + 1,
                     max_level=max_level,
+                    nan_strategy=nan_strategy,
                 ).items(),
             )
         else:
+            nan_strategies = {
+                "fail": False,
+                "allow": True,
+                "convert_null": False,
+            }
+
+            ignore_nan = nan_strategy == "convert_null"
             items.append(
                 (
                     new_key,
-                    json.dumps(v, use_decimal=True, default=str)
+                    json.dumps(
+                        v,
+                        use_decimal=True,
+                        default=str,
+                        allow_nan=nan_strategies[nan_strategy],
+                        ignore_nan=ignore_nan,
+                    )
                     if _should_jsondump_value(k, v, flattened_schema)
                     else v,
                 ),
diff --git a/singer_sdk/mapper.py b/singer_sdk/mapper.py
index cd5faf93c..b243e43fd 100644
--- a/singer_sdk/mapper.py
+++ b/singer_sdk/mapper.py
@@ -121,6 +121,7 @@ def flatten_record(self, record: dict) -> dict:
             flattened_schema=self.transformed_schema,
             max_level=self.flattening_options.max_level,
             separator=self.flattening_options.separator,
+            nan_strategy=self.flattening_options.nan_strategy,
         )
 
     def flatten_schema(self, raw_schema: dict) -> dict: