Lee decided to attend the ceremony "out of a wish that the global festival, which South Korea won the right to host in its third attempt, will become a success," his office said in a statement. The country won the right to host the PyeongChang Games in 2011 when Lee was in office.
An aide also said that Lee decided to attend the ceremony "from the perspective of a greater cause."
The decision ends speculation that Lee could turn down President Moon Jae-in's invitation to the opening ceremony in protest at a prosecution investigation closing in on him. The prosecution reportedly plans to call Lee in for questioning after the Olympics.
Moon offered the invitation last week, and Lee said at the time he would consider it positively. But the mood changed quickly after the prosecution billed Lee as the main culprit earlier this week while indicting one of his close aides on charges of receiving illicit funds from the state intelligence agency.
Lee has denounced the investigation as political retaliation by the Moon administration over the death of late former President Roh Moo-hyun. Roh killed himself in 2009 when Lee was in office amid a corruption investigation that forced him to appear for questioning, a humiliation that many believe led to the suicide.
Lee associates have claimed that the government of President Moon, a key Roh ally who served as Roh's chief of staff, is trying to force the same humiliation back on Lee. Prosecution and presidential officials flatly reject such claims.
Lee's attendance would mark the first time for him to meet President Moon in about two years and three months. They last met at the funeral of former President Kim Young-sam in November 2015.
Lee's wife, former first lady Kim Yoon-ok, however, decided not to attend the ceremony, aides said.(Yonhap)