"It sets up the whole year for me," Calcavecchia said. "It really does."
The 57-year-old Calcavecchia won his fourth senior title and first since 2015.
"I just didn't think it would happen again," said Calcavecchia, the 1989 British Open champion and a 13-time PGA Tour winner. "These guys are so good out here. The level of play is just insane, including Mr. Langer, obviously.
“It's so hard, I can't tell you. I think I made enough putts, and sometimes the good Lord pencils you in, and this week was meant to be."
Langer bogeyed the final two holes for a 70. Tied for the lead after Calcavecchia's bogey on 16, Langer fell back on the par-4 17th when he left a 4-foot par putt to the right.
"I played very well all day really, until that second shot on 17," Langer said. "The bunker shot was pretty good, and then just made a bad stroke. Been putting very poorly all week really. I haven't made anything over 15 feet all week."
On the par-5 18th, the German star drove to the right into pine straw and wood chips and found two bunkers before reaching the green.
"I knew I had to make most likely an eagle or birdie to have any chance," Langer said. "Thought I hit a good tee shot, but it took a vicious kick right and ended up in a horrible lie. I couldn't move some of the whatever this stuff is here. Ended up 50 yards short in the bunker, which is the worst, the hardest shot in golf. From there on it just went downhill. It's just a sad finish to a really great week of golf."
Calcavecchia finished at 16-under 200. He opened with a 64 for a one-stroke lead and birdied the final three Saturday in a 66 that left him two shots clear of Langer. Calcavecchia maintained a share of the lead with the long par putt on 16.
"I played it a cup outside right and I knew I hit it where I wanted to," Calcavecchia said. "When it was about halfway to the hole, I knew it was on a great line and it just went right in the middle."
The 60-year-old Langer won his home event in 2010. He won seven times last season, three of the victories in majors.
"I didn't expect Bernhard to miss that putt on 17," Calcavecchia said. "Every once in a while, very rarely, he gets a little quick with the backstroke and he did it that time. I saw the backstroke and I went, 'Oh, he hit a bad putt.'"
Fred Funk was third at 13 under after a 67. David Toms had a 67 to reach 12 under.
Charlie Rymer finished last in his senior debut, following rounds of 76 and 77 with an 87.