diff --git a/src/py/flwr/cli/new/new.py b/src/py/flwr/cli/new/new.py
index 7eb47e3e3548..bf7ca95ea021 100644
--- a/src/py/flwr/cli/new/new.py
+++ b/src/py/flwr/cli/new/new.py
@@ -22,7 +22,12 @@
 import typer
 from typing_extensions import Annotated
 
-from ..utils import prompt_options, prompt_text
+from ..utils import (
+    is_valid_project_name,
+    prompt_options,
+    prompt_text,
+    sanitize_project_name,
+)
 
 
 class MlFramework(str, Enum):
@@ -81,6 +86,16 @@ def new(
     ] = None,
 ) -> None:
     """Create new Flower project."""
+    if project_name is None:
+        project_name = prompt_text("Please provide project name")
+    if not is_valid_project_name(project_name):
+        project_name = prompt_text(
+            "Please provide a name that only contains "
+            "characters in {'_', 'a-zA-Z', '0-9'}",
+            predicate=is_valid_project_name,
+            default=sanitize_project_name(project_name),
+        )
+
     print(
         typer.style(
             f"🔨 Creating Flower project {project_name}...",
@@ -89,9 +104,6 @@ def new(
         )
     )
 
-    if project_name is None:
-        project_name = prompt_text("Please provide project name")
-
     if framework is not None:
         framework_str = str(framework.value)
     else:
diff --git a/src/py/flwr/cli/utils.py b/src/py/flwr/cli/utils.py
index 4e86f0c3b8c8..6e41abd1492e 100644
--- a/src/py/flwr/cli/utils.py
+++ b/src/py/flwr/cli/utils.py
@@ -14,18 +14,23 @@
 # ==============================================================================
 """Flower command line interface utils."""
 
-from typing import List, cast
+from typing import Callable, List, Optional, cast
 
 import typer
 
 
-def prompt_text(text: str) -> str:
+def prompt_text(
+    text: str,
+    predicate: Callable[[str], bool] = lambda _: True,
+    default: Optional[str] = None,
+) -> str:
     """Ask user to enter text input."""
     while True:
         result = typer.prompt(
-            typer.style(f"\n💬 {text}", fg=typer.colors.MAGENTA, bold=True)
+            typer.style(f"\n💬 {text}", fg=typer.colors.MAGENTA, bold=True),
+            default=default,
         )
-        if len(result) > 0:
+        if predicate(result) and len(result) > 0:
             break
         print(typer.style("❌ Invalid entry", fg=typer.colors.RED, bold=True))
 
@@ -65,3 +70,56 @@ def prompt_options(text: str, options: List[str]) -> str:
 
     result = options[int(index)]
     return result
+
+
+def is_valid_project_name(name: str) -> bool:
+    """
+    Check if the given string is a valid Python module name.
+
+    A valid module name must start with a letter or an underscore,
+    and can only contain letters, digits, and underscores.
+    """
+
+    if not name:
+        return False
+
+    # Check if the first character is a letter or underscore
+    if not (name[0].isalpha() or name[0] == "_"):
+        return False
+
+    # Check if the rest of the characters are valid (letter, digit, or underscore)
+    for char in name[1:]:
+        if not (char.isalnum() or char == "_"):
+            return False
+
+    return True
+
+
+def sanitize_project_name(name: str) -> str:
+    """
+    Sanitize the given string to make it a valid Python module name.
+    This version replaces hyphens with underscores, removes any characters
+    not allowed in Python module names, makes the string lowercase, and
+    ensures it starts with a valid character.
+    """
+    # Replace '-' with '_'
+    name_with_underscores = name.replace("-", "_")
+
+    # Allowed characters in a module name: letters, digits, underscore
+    allowed_chars = set(
+        "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789_"
+    )
+
+    # Make the string lowercase
+    sanitized_name = name_with_underscores.lower()
+
+    # Remove any characters not allowed in Python module names
+    sanitized_name = "".join(c for c in sanitized_name if c in allowed_chars)
+
+    # Ensure the first character is a letter or underscore
+    if sanitized_name and (
+        sanitized_name[0].isdigit() or sanitized_name[0] not in allowed_chars
+    ):
+        sanitized_name = "_" + sanitized_name
+
+    return sanitized_name