MLB fans freaking out over their teams' new jerseys can take a chill pill ... 'cause Eric Hosmer tells TMZ Sports that even though they don't look so hot right now, he's sure the league will get it fixed by Opening Day.

The uniforms have been widely criticized by seamheads and even players all over the country after they were debuted earlier this month out at spring training.

Many have noted the new Nike designs have some serious flaws -- namely, the lettering on the back is too small and the positioning of some of the logos just doesn't feel right.

Plus, diehards have hated the way the pants have appeared to be see-through.

When we spoke with Hosmer about the hot-button topic this week ... he said he understood fans' concerns, admitting the jerseys do look "a little bit" like knockoffs. But, he added that he's almost positive changes will occur before Week 1.

"There's no doubt in my mind that they'll get it right before Opening Day," he said. "And those guys will be looking like Big Leaguers come April 1 -- whenever the first game is."

The former World Series champ also spoke with us about Shohei Ohtani's new, massive Dodgers contract -- and he gave us his prediction for who he thinks will be the toughest team to beat in 2024.

As for what he's up to now after officially retiring earlier this week ... he's started his own sports media company with his former teammate, Anthony Seratelli, called "MoonBall Media."