The 28-year-old will be well known to Chairboys fans after scoring twice against the Blues atAdams Park last season for Chesterfield.
Morgan started his career at Colchester United before enjoying spells at Reading, Luton Town and Leyton Orient amongst others.
He finished last season on loan at Oxford United and is eligible for selection against former side Chesterfield on Saturday.
“In recent weeks we have lacked creativity and a goalscoring threat so we needed to address that by creating competition up front,” Gary Waddock told Chairboys Player.
“I’m delighted. Dean Morgan is a very good player as we have seen in recent seasons and he has always played well against us. He will be a very good addition to our club.”
Waddock added: “Bevs (Stuart Beavon) has gone to Preston and Don (Woodward) said to me that the club would re-invest some money into the squad and he has been good to his word.
“He's also allowed us to bring (Jo) Kuffour into the building so he deserves great credit for that.”
Morgan will wear number 20.