Guthrie will make $5 million next season, $11 million in 2014 and $9 million in 2015.
The 33-year-old Guthrie was acquired in a midseason trade from the Colorado Rockies, where he'd been just 3-9 with a 6.35 ERA. He wound up going 5-3 with a 3.16 ERA in 14 starts in Kansas City, including a 4-0 mark with a 2.17 ERA over his final 11 outings.
The Royals have been trying to piece together a rotation after struggling mightily last season. They've already traded with the Angels for right-hander Ervin Santana and claimed right-hander Chris Volstad off waivers from the Cubs.