Charlie Axel Woods was born on Sunday, the 33-year-old American told his official website.
"Elin and I are thrilled to announce the birth of our son Charlie Axel Woods," said Tiger. "Both Charlie and Elin are doing great and we want to thank everyone for their sincere best wishes and kind thoughts.
"Sam is very excited to be a big sister and we feel truly blessed to have such a wonderful family."
The couple were married in 2004 and their first child, daughter Sam Alexis, was born in June 2007.
Woods has been out of action since undergoing reconstructive knee surgery following his US Open win in June.
The 14-times Major champion is expected to return next month to prepare for the US Masters which starts on April 9.
Last week Woods said his comeback would depend largely on the timing of his son's birth.
The Masters, the opening major of the year, has long been his next golfing priority and the March 12-15 WGC-CA Championship in Miami is likely to feature in his preparations.