They also confirmed that left-handed specialist Clay Rapada has been designated for assignment to clear a spot on the 40-man roster.
Guthrie said the deal was pretty much done Saturday night.
"I talked to my agent, Brodie (Van Wagenen) and all parties involved and they let us know that's what was going to happen," he said.
"At first, you're a little bit sad thinking about the people you're leaving behind. I've always been grateful to the Orioles fans and even more so now that I'm looking back on it. I really enjoyed interacting and playing in front of them as much as you could ever imagine. This is my favorite team I played on with the Orioles in terms of the 25 guys and the coaches, and I'll miss them probably more than I even realize right now. The friendships have meant a lot to me. Those are the things that come to mind. And I really believe this team has a lot of good parts. I think they'll win and that will be hard for me. It will be hard not being part of it when I see them winning, which I expect them to do."
Guthrie has lots of memories from his five seasons in Baltimore. "Hundreds of them," he said.
"And I have a pretty good memory, as my wife will tell you. There aren't many things the last five years that I don't remember. The ones I think of right away include my first opening day at Camden Yards, seeing the festivities, having never been on an opening day roster and seeing what it's all about in that city and that community. And my great teammates. Even Matt Wieters being called up to the big leagues is something I'll always remember, the excitement for that. There are countless memories and I don't anticipate forgetting those moments ever.
"I think everything that happened the past five years helped me grow and my family grow. My five years in Baltimore are a huge part of my family's lives and the foundation for what's going on the rest of our time here."
Guthrie will face some challenges pitching at Coors Field, but he's ready for them.
"I'm excited about it," he said. "I think it presents challenges like any ballpark. Camden Yards at times can be a challenging ballpark to pitch in, especially considering the competition that comes day in and day out from the East.
"From what I gather and from what I've heard talking to pitchers in the past, they feel like it's pretty much like any other place. The ball just carries a little bit more. There's more motivation to pitch down in the zone, which is what you need to do to be successful in any park. I'll just have a heightened awareness, and that will be my focus."
Guthrie agreed to an $8.2 million deal with the Rockies, avoiding the arbitration process in his final year before free agency.
"That was a big part of the deal," he said. "It made sense to all parties if this trade was going to happen to not throw the Rockies in an unprepared situation. My hearing was scheduled for today. All parties are pleased with the negotiations and we're ready to move on. It's important for this to be a step forward and to not worry about a lot of other things."
Getting the chance to bat in the National League is "probably the least exciting part of it for me," Guthrie said, laughing. "I don't think I wield the stick as well as most baseball players. I was blessed with a terrible bat in Little League and Babe Ruth and high school. It hasn't gotten any better in the big leagues, surprisingly.
"I'm pretty sure I swung at every pitch I saw. I'll work on my eye and try not to do that anymore."
Guthrie didn't dismiss the possibility of re-signing with the Orioles as a free agent. They never showed interest in giving him a long-term deal. Maybe that will change.
As for Rapada, he's held left-handed batters to a .090 average since 2010. But again, the Orioles can't afford to carry a specialist in their bullpen when they'll likely need multi-inning guys to assist the rotation. Same issue as last season.
By my math, the Orioles have 12 new players on the 40-man roster since the end of the 2011 season.