Kittle, who was listed as questionable, has been dealing with swelling and pain in the calf since the Niners' Week 1 win against the Detroit Lions. He was a limited participant in Friday's practice after he did not take part on Wednesday or Thursday.
After Friday's practice, Kittle said he would "do everything I can" to be able to play in Sunday's pivotal early-season matchup with division rival Seattle.
"And then if the body says I can go, I'll be out there," he said.
Kittle, 27, is second on the team in receptions (15) and receiving yards (187) through three games.
Niners running back Elijah Mitchell, who is listed as questionable with a shoulder injury, is inactive for Sunday.