Mohsni netted four goals in five games during the month, including a hat-trick in the 3-0 home victory over Barnet to leave the Shrimpers in with a chance of securing automatic promotion.
Southend manager Paul Sturrock told the club's official website: "Bilel has been magnificent for us this month, not only in attack but also getting his head onto everything in defence from set-pieces.
"I'm really pleased for Bilel and hopefully he can play a vital part in helping us secure promotion this season."
