Mafi featured in all of Tigers’ Aviva Premiership games during March, helping Tigers move into the top two in the table with bonus-point wins against Gloucester Rugby, London Irish and Worcester Warriors.
He scored a try in the 36-3 win over Gloucester at Welford Road, while his set-piece play and work in the loose has been a feature of Tigers’ recent run of eight wins in all competitions.
And after receiving his award at Oval Park on Tuesday, he was quick to praise the work of his Tigers team-mates.
“I am very surprised to win it but it feels really good and I am delighted,” he said. “A lot of credit has to go to the boys at Leicester, who are playing well together and working hard for each other.
“Aviva have given me £500 to donate to the charity of my choice and I have selected the Matt Hampson Foundation.”
Richard Cockerill, the Tigers director of rugby, said: “Steve has improved a lot since he first got here. He has a lot of athletic potential and he is learning all the time.
“He has done an outstanding job for us. We hope we can keep him for a long time.”
Paul Morgan, Player of the Month panel chairman, said: “Steve has made a huge impact on the Aviva Premiership this season and it was only a matter of time before he was honoured in this way.
“He’s an all-action, non-stop rugby player who has brought 100 per cent commitment to the Leicester Tigers challenge this season.”