Software tycoon Ahn Cheol-soo, who dropped out of the presidential race last year, plans to run for a National Assembly seat in a by-election in the Nowon district in northeastern Seoul on April 24.
Ahn's former campaign aide Song Ho-chang on Sunday told reporters that Ahn will return to Korea on Sunday after two months in the U.S.
Another aide said Ahn wants to form his own political party before another by-election takes place in October.
Ahn is expected to stand against candidates from both the ruling Saenuri Party and main opposition Democratic United Party.
Ahn dropped out of the presidential race at the last minute after complaining about shenanigans in attempts with the DUP to field a single opposition candidate.