Can forehead Botox affect singing?

While the Botox will not affect your voice or vocal delivery, it would affect the facial muscles that control your expressions while you sing.  One nice thing about Botox is that you can always customize the procedure to each patient’s unique needs.  In your case you may want to consider injecting fewer units, which would leave you with a greater range of facial movement.  You may not be able to achieve the full extent of the results you were hoping for, but you can absolutely improve wrinkles and lines while maintaining a certain range of movement.  

Thank you for your question, I can assure your Botox will not affect your ability to sing.  Please make sure you seek treatment from a board-certified dermatologist.