Gilbert Arenas' baby mama Laura Govan is 100% behind him making a big comeback to the NBA next year ... and she tells TMZ Sports, he's still got what it takes to light it up in the league.

With Gilbert recently saying he's flirting with the idea of a comeback, the "Basketball Wives" alum tells us hanging up the towel would be a HUGE waste of talent!

Laura says Gilbert "still has it in him" to play and said she doesn't know why he isn't back already because "he's still good as hell."

It's interesting, considering just a few weeks ago Gilbert told us he would NEVER play pro basketball again because he doesn't want to and he doesn't need the money.

After we shot Laura, Gilbert told our friends at Bleacher Report he's changed his mind and would consider a comeback.

Stay tuned ...