The Batman star has three sons: Alfie with his first wife Lesley Manville, and Gulliver and Charlie with his third wife Donya Fiorentino. Oldman and Fiorentino's split in 2003 resulted in the actor being awarded full custody of both teenage boys.
"I asked myself a very simple question. Am I a dad who's going to be away working all the time? Or am I going to be a dad who's around at home?" the actor told UK Vogue magazine.
"I decided to be at home," he added. "It set a new course for the ship."
Alfie is now in his 20s, but Oldman admitted he still worries about what his son made of his childhood. He said that as a result, he now works hard to provide a good life for both Gulliver and Charlie.
"I had really felt that I had not done it successfully with my first son, although our relationship was always good," he explained.
"But I felt that I had been given the gift of a second chance. I'd been awarded these children, by the court - which is unheard of in California - and I felt that I now had these boys for a reason."
Oldman stars in Christopher Nolan's The Dark Knight Rises, which is released in the UK and US on July 20.
Photo gallery - The Dark Knight Rises in pictures: