Baek Il-sub began his acting career in 1965 at 21 years old. His decades-long career has produced a long list of television dramas and films including the 1975 movie Light Flower, in which he was named Best Actor at the 11th Baeksang Arts Awards. In 1992, he became part of the hit MBC series Sons and Daughters. From 1995 to 1997, he made appearances in four MBC dramas, namely Do You Remember Love, The Fourth Republic, Salted Mackerel, and Golden Feather. He also starred in KBS1’s long-running drama Love on a Jujube Tree from 2001 to 2007. In 2002, he was cast in the SBS drama Glass Slippers as the grandfather to Kim Hyun-joo and Kim Ji-ho’s characters. In 2008, he received an Achievement Award for his work in the KBS2 family drama Mom’s Dead Upset. The series was also hailed Best Drama at the 45th Baeksang Arts Awards. In 2013, he joined the tvN travel reality show Grandpas Over Flowers, which won the Best Entertainment Program citation at the 50th Baeksang Arts Awards. He and his co-stars also received the Variety Icon trophy at the 2016 tvN10 Awards.

In November 2016, Baek Il-sub said during a talk show guesting that he “has graduated from marriage.” Called jolhon in Korean, this type of arrangement refers to couples staying legally married but living like a single individual. Baek Il-sub and his wife have a son and a daughter.