Oakland Raiders 1st Round Pick Buys House for Mom (PHOTO)

Mother's Day came in January for Karl Joseph's mom ... the Oakland Raiders rookie safety just bought her a brand new house in Florida ... TMZ Sports has confirmed.

The 14th overall pick in the 2016 NFL Draft was laser-focused on hookin' up his mom with something nice after he signed a 4-year $12 million deal ... and pulled the trigger when he found her dream home.

We spoke with Karl's agent, Chafie Fields, who tells us the home is in central Florida where he grew up after the family moved to the U.S. from Haiti.

"He comes from very humble beginnings," Fields says ... "Ultimately, his goal was being able to provide for his mom."

"He didn't want to buy himself a car. Didn't want to buy himself a house. He wanted to get his mom a house."

Fields says his team helped with the house hunt but ultimately Karl made the final call -- "He wanted to see the house for himself, so that's why we waited until after the season."

"He has brothers and sisters that still live at home. He wanted to do this for all of them."