The hour-long, yet-to-be-titled show is to air Mondays through Thursdays at 11 p.m. It will be followed by "Lopez Tonight," which will shift to a midnight time slot.
O'Brien began talks in earnest with TBS just last week after Lopez personally called him to ask that he consider joining the network's late-night line-up, the network said.
"I can't think of anything better than doing my show with Conan as my lead-in," Lopez said in a statement. "It's the beginning of a new era in late-night comedy."
"In three months I've gone from network television to Twitter to performing live in theaters, and now I'm headed to basic cable. My plan is working perfectly," O'Brien added.
"Conan has been the comedic voice for a generation. TBS already has a huge audience of young comedy lovers, and Conan's show will give these fans even more reasons to watch our network," Steve Koonin -- president of Turner Entertainment Networks -- remarked. "For decades, late-night TV has been dominated by broadcast television. Now, with a young audience and a growing late-night lineup, TBS is set to be the choice of comedy fans for years to come."
NBC booted Jay Leno as host of "The Tonight Show" at the end of last season and gave the position to O'Brien -- then the host of "Late Night with Conan O'Brien" -- to keep O'Brien from moving to another network. NBC then offered Leno a nightly, hourlong 10 p.m. series.
But when the prime time "Jay Leno Show" failed to be a strong lead-in for local news broadcasts, NBC announced it would push Leno's show back to 11:35 p.m., shorten it to 30 minutes and air "Tonight" at 12:05 a.m. However, O'Brien said he would not remain on "Tonight" if it was bumped to 12:05 a.m. and left the network, paving the way for Leno's return as "Tonight" host. One of the stipulations in O'Brien's exit contract with NBC was that he not star in another television show until next fall.