Fox participated in a noncontact practice on Tuesday and told reporters afterward there's "no ifs, ands or buts. I'm playing."
Fox suffered the injury, which the team has called an avulsion fracture, late in Sunday's Game 4 loss to the Warriors. He was seen shooting with a splint on the injured finger in Tuesday's practice.
"For me right now, it's just tolerance of the pad on my finger, making sure I can shoot the ball," Fox said. "As we got going, as the pain started going away. I feel like I could do my normal shot. I think I'll be good."
Fox said he had no problems dribbling and passing and the biggest question was making sure he could deal with the pain and make his shot.
He said he felt optimistic after the swelling in the finger went down in the past day and the pain has become manageable.
"At the end of the day, I'm fine," he said. "I can shoot the ball. At this point in the season, everybody has something. Obviously a bone might not be chipped, but something is hurting on everybody. So you go out there and you still play the game. I'm not worried about it."
Kings coach Mike Brown said it will be a joint decision over whether Fox can ultimately play in Game 5. He was upgraded from doubtful to questionable on Tuesday night.
"It's got to be me agreeing for him to play, him agreeing to play, our medical staff agreeing [for him] to play and our team doctors doing the same thing," Brown said. "So it's a joint deal. It's not just him making it, it's not just me making, we all have to be on the same page with it."
Fox got injured on a drive midway through the fourth quarter of Game 4. He remained in the game after the injury and even made a key 3-pointer in the closing minute before Sacramento lost 126-125. Fox passed out of a double team on the final possession and the Kings lost when Harrison Barnes missed a 3-pointer at the buzzer.
Fox is in the midst of a stellar series, averaging 31.5 points, 6.0 rebounds and 7.0 assists in his playoff debut. He leads the Kings in points and assists and is second in rebounds through four games this postseason.
The series returns to Sacramento for Game 5 tied at 2-2.
The Associated Press contributed to this story.