Maier was designated for assignment on Wednesday as the Royals brought up two pitchers from Triple-A Omaha: right-handers Nate Adcock and Louis Coleman.
Right-hander Vin Mazzaro was optioned to Omaha on Tuesday night after a 6-3 loss to the Blue Jays.
There's a 10-day period for Maier's fate to be determined, including going through waivers. He left Toronto for home after being informed of the move.
"He's as perfect a teammate as you could ever want on your team," manager Ned Yost said. "He's always ready, always prepared, never complained, just worked hard, just wanted to win."
Maier's playing time had dropped markedly in the last two seasons. In 2011, with Alex Gordon, Melky Cabrera and Jeff Francoeur playing well and injury-free, Maier got into just 45 games with only 95 at-bats, hitting .232.
A left-handed hitter, Maier appeared in 32 games this season and had a .172 (11-for-64) average with two home runs and seven RBIs.
"We've got so many young outfielders we want to look at," Yost said. "He was a great guy to have on your team as your fourth or fifth outfielder. But being mostly left-handed in the outfield, we needed a right-handed bat in [Jason] Bourgeois and we've got [Jarrod] Dyson, [Lorenzo] Cain's coming back soon and we've got [Wil] Myers on the horizon."
A .248 hitter in his six years and 360 games with the Royals, Maier was an excellent outfielder and once played 190 consecutive games without an error. In 2009, he had 11 outfield assists to lead all Major League rookies.
His busiest seasons were 2009 and 2010, when he played 127 and 117 games, respectively. In those years he found himself filling in for the injured players like Coco Crisp, Jose Guillen, Rick Ankiel and David DeJesus.
A right-handed thrower, he also was used as an emergency pitcher twice with the Royals, pitching an inning at Boston in 2011 and an inning against Cleveland this year. Both were scoreless.
"He was a great teammate," Gordon said. "The last two years he really hasn't got the consistent playing time, but you never heard him complain. He was great in the clubhouse, great for our team chemistry, just a great person in general.
"He was probably one of my first good friends in pro ball. I started off with him in Double-A and played with him for six years. It's sad to see him go, but that's part of the game and I'm sure someone is going to be excited to pick him up, because he's a great player and he's going to make some team happy."
"He worked harder than anybody else in this clubhouse," said third baseman Mike Moustakas. "He was always one of the first guys here, always one of the last guys to leave. A great leader, just a great guy to be around."
Yost believes that Maier could be valuable addition to another team, where he could get more playing time.
"He's a perfect guy for a National League team where you've got to use your switches, he can play all three outfield positions equally well, he can give you a smart at-bat, he's a good baserunner," Yost said. "He does a lot of things really well but you kind of get stagnated when you don't play."
Dick Kaegel is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.