It's Baltimore's fourth walk-off win in the past five games.
Beavers now joins teammates Emmanuel Rivera and fellow rookie Samuel Basallo as the third O's player to hit a walk-off in that span.
After going scoreless the first seven innings, Baltimore put a run on the board in the bottom of the eighth inning thanks to a Jackson Holliday RBI single. That's all that was needed to send it to extras, where the team loaded the bases for Beavers to walk it off.
Beavers finished the night going 2-3 at the plate - the only O's player with multiple hits - improving his already impressive slash line to .305/.453/.441 paired with his lone home run and seven RBI.
O's relief pitcher Albert Suarez earned his second win of the season after throwing a shutout in the top of the 10th, while Pirates relief man Kyle Nicola earned the loss. Baltimore's starting pitcher Tyler Wells made his season debut after returning from injury, tossing 6.2 innings, giving up just one run on one hit while striking out six and walking one.
He received a standing ovation from the Orioles faithful after being taken out in the seventh inning.
As for the other side, it was another day, another start for Pirates ace Paul Skenes, where he pitched a shutout only for his team to provide hardly any run support yet again, lowering his already MLB-best earned run average down to an unbelievable 1.92.
The O's will look to sweep the series on Thursday before heading up to Toronto for a three-game slate against the division rival Blue Jays.