“He was only 23 and the news of his sudden and untimely passing has been a shock to us all. Christian came to the club in January and proved to be an extremely popular member of the squad.
“His loss will be painfully felt by all who had the pleasure of knowing him. The club would ask everyone to respect Christian’s family’s privacy at this sad time.”
The cause of his death wasn’t disclosed.
The English professional footballer, who started his career with non-league Brentwood, also had spells at Millwall and Motherwell before joining Morecambe following his release from Crewe in January.
Motherwell chairman Jim McMahon also expressed his shock at the sudden death of Mbulu.
He said: “We are shocked to hear of the news of Christian’s death.
“He was such a friendly, pleasant and dedicated young man who we loved having around Fir Park.
“Our thoughts are with his family during this incredibly difficult time. We hope their privacy is respected by everyone as they try to come to terms with their loss.”