"I am deeply aware of the disappointment and hurt that my infidelity has caused to so many people, most of all my wife and children," Woods, the top-ranked golfer on the PGA Tour, said on his Web site late Friday.
"I want to say again to everyone that I am profoundly sorry and that I ask forgiveness. It may not be possible to repair the damage I've done, but I want to do my best to try."
The 30-year-old married father of two children said his family needed "safe haven" for "personal healing."
"After much soul searching," he said, "I have decided to take an indefinite break from professional golf. I need to focus my attention on being a better husband, father and person."
Woods asked for privacy and thanked "those who have offered compassion and concern during this difficult period."
The golfer's extramarital affairs came to light after he was in a car accident outside his Windermere, Fla., home early Nov. 27. He hit a fire hydrant and a tree on a neighbor's property and was charged with careless driving.
The PGA Tour expressed support for Woods.
"His priorities are where they need to be and we will continue to respect and honor his family's request for privacy," PGA Tour Commissioner Tim Finchem said. "We look forward to Tiger's return to the PGA Tour when he determines the time is right for him."