The 21-year-old is yet to start a Premier League game but capped a fine performance with a goal in Sunday's FA Cup fifth-round win at Huddersfield.
And Martinez is ready to let McManaman loose as second-bottom Wigan aim to make up a three-point shortfall to safety between now and the end of the season.
He said: "Callum is a real example of what we want in our football club - youngsters that, if they work well, if they apply themselves well, are going to have opportunities.
"He's been working really hard and enjoying his football, and what he did against Huddersfield is going to help the team because that talent is welcome in any group of players.
"We're delighted that Callum is developing into an impressive young footballer and he's going to be very important for us until the end of the season.
"He's a player who can create something out of nothing, and those players are quite rare.
"We need to understand he is still a young man and he's still developing, and he deserves that time and that patience to allow him to be as good as he can be.
"But clearly this season he's put himself in a position where, as you saw in the last game, he can be effective."