The French-Tunisian centre-back has agreed a two-year deal with the Ibrox club after impressing while on trial this summer.
The 26-year-old will be registered on September 1 when the club's signing embargo is lifted
Mohsni played in defence during friendlies in recent weeks but has no qualms about moving further up the park.
He told the club's official website: "I'm a centre-back and I feel most comfortable there but I can play in an attacking position too.
"If the manager needs me to, I will play there because I did that when I was at Southend and Ipswich.
"When players were injured, they sometimes needed my height to flick the ball on and I'd be happy to do that again.
"When the manager talked to my agent, he said if we are losing or maybe drawing he might want to put me up front.
"But for the moment I am concentrating on being a centre-back and I am most comfortable there plus we have some good strikers already."
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