He said his attorney filed paperwork in Ohio to make the name change legal.
"If you ask the fans around San Francisco, the Bay Area, or anyone that's a fan of me, they call me Donte Hitner any way," he told the 49ers' website. "Everything we do is for the fans right? It's all entertainment. We all understand that. It's entertainment, but that's what I do, it's my game. Along with some things that happened recently, that's why I went with it."
Whitner, as he was known last week, received a $21,000 fine from the league for a hit on St. Louis Rams receiver Chris Givens in the fourth quarter of last Thursday's game. Hitner plans to appeal the penalty.
The 28-year-old, who made the Pro Bowl last season, said he received permission from his mother to change his name. His mom said no the first time he asked her in the offseason.
"I'm forever going to be her son and her little boy, so I have to listen to what she says," he said. "After all of these hits and people talking about it, I asked her again three nights ago. She said, 'I don't have a problem with it, go ahead.' So I went ahead and did it yesterday."
He said despite the name change, he remains committed to playing within the rules. He will sell T-shirts that read #LegalHitner.
"I'm not out there head hunting, hitting guys helmet to helmet," he said. "I want to show guys can hit hard and bring fear doing it the legal way. This is a tough game. This is a game for grown men. When we signed up for that, we all know that. If you don't want to play football, you don't want to be physical, you don't want to be hit, don't come around guys that like to hit. That's the game of football. Just do it the right way."
According to ESPN.com, an in-season name change could prove expensive for an NFL player. League rules require the newly renamed player to buy all existing merchandise bearing his old moniker.