The Canaries' defender wants the Sierra Leone striker to make his loan move from MLS side Sporting Kansas City permanent after impressing in his short spell at the club.
The forward arrived at Carrow Road from MLS side Sporting Kansas City temporarily in January and has made an impressive start to his short spell with Chris Hughton's side, coming off the bench to score against Everton in just his second Premier League appearance.
Since then, the 28-year-old has forced his way into the Canaries' starting lineup, and his teammate is keen to see the powerful Sierra Leone striker remain with the club after his loan expires on May 6.
"It is the manager's decision but yes, I'd love Kei [to stay]," Martin told reporters. "I think he has brought so much here. He has been a breath of fresh air, really.
"And I think he's not just a good lad, he's a really good player. He has been really effective and I think he did great for us again at Sunderland.
"I think he's been brilliant. He has surprised all of us, to be honest. You never know what you are going to get. MLS is getting better and better but you're never sure what you're getting.
"He has not had games and he had a bit of time off before he came over, so for me he will only keep getting better and it is up to him to decide his future, really. If he keeps it up, then I'm sure we will be more than interested in keeping him."