The 54-year-old Showalter will be formally introduced at a news conference on Monday, and will make his managerial debut in the O's series opener against the Angels on Tuesday.
"Buck Showalter's proven track record makes him the right choice for manager of the Orioles and we are thrilled to add a two-time Manager of the Year to our organization," president of baseball operations Andy MacPhail said in a press release.
"We believe Buck's extensive experience and expertise will be a major benefit to us as we look towards a more successful future."
Showalter, who has a career 882-833 managerial record in 11 seasons with the Yankees, Rangers, and D-backs, has a tough task in the present. The Orioles entered Thursday's game in Kansas City a Major League-worst 31-70 and are well on their way to their 13th consecutive losing season.
"My job with ESPN allowed me to follow this organization closely over the last several years," said Showalter in a release, "and although the current record may seem to indicate otherwise, I see enormous potential with this club. I look forward to the challenge of competing in the American League East."
The 54-year-old Showalter, who friend and current Orioles pitcher Kevin Millwood, called "the most prepared individual" he's ever met, will be the Orioles' 10th manager since Peter Angelos became the principal owner of the franchise in August 1993. He will assume the full-time position vacated by Dave Trembley, which has been occupied by interim manager Juan Samuel since June 4.
"I think he's definitely here to change things," starter Jeremy Guthrie said of Showalter, who is known for his strict, no-nonsense approach. "It makes sense for [the organization] to bring in fresh perspective, bring in a different attitude, someone who hasn't necessarily been part of the Orioles, but has seen what we have gone through the past years."
Showalter met with Orioles brass several times, including a nearly three-hour formal interview on June 23, and given MacPhail's emphasis on experience, the meticulous former manger quickly emerged as the front runner. The Orioles also interviewed MASN broadcaster and ex-Orioles catcher Rick Dempsey, former Indians skipper Eric Wedge and ESPN analyst Bobby Valentine, who later withdrew his name.
"I've heard good things [about Showalter]," said second baseman Brian Roberts, the longest-tenured Oriole. "I heard he's very prepared, and certainly his reputation over the years is very good. He's managed winning teams. Hopefully, it will be something good for us."
Showalter was named AL Manager of the Year twice -- in 1994 and 2004 -- and is credited in many circles for jump-starting the Yankees' dynasty of the late 1990s, and both New York and Arizona won the World Series the year after he left. Showalter's most recent managing job was in '06 with the Rangers, which is where he struck up a close relationship with Millwood, who still plays golf with him in the offseason.
"I think cutting back on some nonsense [around here] wouldn't be a bad thing," Millwood said.
"Obviously something needs to change, and I think Juan did a good job, but sometimes [you've] got to take someone from the outside coming in to really make the kind of change that [the Orioles] need."
Showalter spent four years at the helm in Texas, posting a 319-329 mark, and led Arizona to a 100-win season in '99. He led the Yankees to a first-place finish in '94's strike-shortened season and managed the AL All-Star Game the following summer.
"I owe a lot of my early success to Buck believing in me as a young player," said Yankees first baseman Mark Teixeira, who played for Showalter in Texas.
"The [Orioles have] some young talent, but hasn't been able to win. You bring a guy like Buck in to make those young players believe in themselves, teach them how to win, and then see what happens in the future.
"I know there's a lot of feeling surrounding him, and how he manages and controls, and all the things he does within the framework of an organization," Mets righty R.A. Dickey said of Showalter.
"But as far as I'm concerned, I would play for him any day. He was the guy that gave me my chance [in Texas] when other people said, 'You weren't good enough.' And I appreciated that."
Showalter will spend the final two months of the season implementing a plan to right a franchise that has underperformed and never recovered from a 2-16 start under Trembley this season. Trembley was dismissed on the heels of a winless six-game road trip -- with series sweeps in Toronto and New York -- and at the time the last-place O's had a Major League-worst record of 15-39.
Trembley, who took over as Orioles manager on an interim basis on June 19, 2007, after Sam Perlozzo was fired, compiled a 187-283 record. His .398 winning percentage is second-worst of any manager in Orioles history -- better only than Jimmy Dykes (.351 in 1954).
Samuel was named Trembley's replacement -- becoming the first Latin-born manager in Orioles history -- and at times he seemed to reinvigorate a beleaguered Baltimore squad. The Orioles completed a four-game sweep at Texas heading into the All-Star break, but have won just two games since.
"With the situation we are in, it is nice to know that we are going to have a permanent solution as far as the manager goes," said outfielder Nick Markakis. "It's been tough. Juan's been doing a good job, but the organization feels that we needed to have a long-term manager. And I think, for the team and the organization, it's the right decision."
Added Guthrie: "It will certainly provide stability and give us a foundation to start building off. As it is, it feels like maybe we've been building kind of on a temporary foundation. But now Buck will arrive next week and he will begin his project of getting this team back where it should be."
Brittany Ghiroli is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.