Thomas has missed three of the Dolphins' seven games this season with a nagging hamstring injury. He sat out the Dolphins' Week 8 loss to the New York Giants after playing the two previous weeks. He had been listed as questionable for Sunday.
As expected, Dolphins cornerback Vontae Davis also is inactive for non-injury reasons. NFL.com reporter Jeff Darlington revealed Saturday that Davis was involved in a confrontation with Brandon Marshall this week. The team hasn't confirmed the reason for Davis not playing against the Chiefs.
Running back Steve Slaton and defensive end Phillip Merlin are among the other players inactive for Miami.
McGraw hurt his shoulder in last week's 23-20 overtime win over San Diego. Arenas, who has emerged as the Chiefs' best return man, had been listed as questionable with an ankle injury.
Visit www.nfl.com/inactives to see inactive players in every Sunday game.
The Associated Press contributed to this report.