The Royals, moving quickly to bolster their rotation, acquired right-hander Ervin Santana from the Angels on Wednesday.
The Angels needed to decide by Wednesday whether to exercise Santana's $13 million option for 2013.
The Royals presumably will pick up that option. It is not yet known whether the Angels are including cash in the deal to cover part of Santana's salary.
The Royals are sending LHP Brandon Sisk to the Angels. Sisk, 27, spent last season as a reliever at Triple A, posting a 2.54 ERA in 50 games.
Santana, who turns 30 on Dec. 12, was 9-13 with a 5.16 ERA and allowed a major-league leading 39 home runs.
The Angels also have been trying to trade right-hander Dan Haren, who is in a similar contractual position to Santana.
The deadline for the team to decide on Haren's $15.5 million option for 2013 is Friday.
Haren, 32, was 12-13 with a 4.33 ERA last season, suffered from lower back tightness and showed a decline in fastball velocity.