Eric Hosmer delivered the game-tying two- run homer in the eighth, then Alcides Escobar won it with an RBI double in the ninth, as Kansas City rallied to down Baltimore, 4-3, in the third test of a four-game set.
Down 3-1 against Wei-Yin Chen, Lorenzo Cain singled with one out and Hosmer tied the score with his blast to right center.
Against Darren O'Day (5-1) in their last turn, David Lough singled with one out and came home with the winning run when Escobar roped a hit which caromed off the fence in center.
"They're an extremely tough team. We played very well last night and very well tonight. It is good to beat them," Royals manager Ned Yost said.
Luke Hochevar (3-1) tossed a scoreless top of the ninth. Ervin Santana worked the first eight frames, allowing seven hits and three runs -- one earned.
Hosmer added an early solo homer, with Billy Butler and Escobar chipping in a pair of hits each for the Royals, who have taken two of the first three in the series.
Matt Wieters slugged a two-run shot and Adam Jones knocked in the other run for the Orioles, while Chen gave up three runs on seven hits in 7 1/3 innings.
Hosmer's first-inning homer gave the hosts an early edge. However, Chen set down 12 in a row until an Escobar single in the fifth.
In the fourth, Baltimore took the lead after Jones reached on Hosmer's fielding error and scored on Wieters' two-out, two-run homer.
The Orioles loaded the bases in the eighth thanks to singles from Brian Roberts and Nate McLouth, a Manny Machado sacrifice and intentional walk to Nick Markakis.
"We added on that run in the eighth, I thought that was going to be enough, but they came back and got us. it was a tough night," said McLouth.
Jones then grounded into a fielder's choice from short to second, allowing Roberts to cross the plate for a two-run spread.
Hosmer posted his second multi-homer effort in less than a month, after going deep twice in a 9-3 win at Minnesota on June 28 ... To make room for pitcher Francisco Rodriguez, the Orioles made a late roster move to option infielder Danny Valencia to Triple-A Norfolk, while also signing outfielder Dariel Alvarez to a minor league contract and assigning him to Single-A Frederick.