- April 4 - Barmes hits a game-winning walk-off home run off Trevor Hoffman of the San Diego Padres in front of a sell-out crowd on Opening Day at Coors Field.
- May 2 - MLB selected Barmes as the National League Rookie of the Month for April. Barmes, who hit .410 with four home runs and 14 RBI, also became the third player in MLB history to hit .400 or better in March/April, joining the New York Mets' Willie Randolph in 1980 and Montreal Expos' Andres Galarraga in 1986.
- June 8 - Barmes suffered an injury that sidelined him until September after breaking his left collarbone in a fall while carrying a large slab of meat given to him as a gift by Todd Helton up the stairs in his apartment building in June 5. (Barmes initially told the team and the press that he got hurt carrying groceries, but later admitted that this was not the truth. He claimed that he was trying to prevent Helton from being embarrassed.) Barmes, who was leading National League rookies in most offensive categories, underwent surgery on June 7. He was hitting around .400 and led the major leagues in batting average for the first six weeks of the season. After a mild slump, he was still leading NL rookies in hitting (.329), runs (40), hits (74), doubles (16), home runs (8) and RBI (34) up until the time of his injury. His Rookie of the Year candidacy, however, was ruined by his freak injury, which he called "the craziest thing that's happened to me, by far." However, Barmes still finished eighth in the National League Rookie of the Year voting for the season.
Barmes entered the 2006 season with high expectations. Many predicted a repeat of the beginning of the '05 season for Barmes in '06. Although Barmes set career highs in a number of offensive categories, his '06 season was widely considered a disappointment. He managed a subpar .220 batting average (the lowest of any starter in baseball) with only 7 home runs and a .264 on base percentage.
As Spring Training prior to the 2007 season began, Barmes was informed that recently drafted prospect Troy Tulowitzki would be competing with him for the starting role in '07. After a Spring performance that mirrored his unimpressive '06 season, Tulowitzki was awarded the starting shortstop position with the Rockies. Subsequently, Barmes began the season with the Rockies Triple-A affiliate, the Colorado Springs Sky Sox. After an injury to starting second baseman Kazuo Matsui, Barmes was recalled to the Major League roster on April 15. After wearing jersey number 12 throughout his tenure in the Majors, Barmes switched to number 21 for the '07 season after veteran Steve Finley chose number 12 for the season.
Not long after being recalled, Barmes was sent down to Triple-A on May 1.
- Selected by Colorado Rockies in the 10th round of the free-agent draft (June 5, 2000 - signed June 9, 2000).