He was twice selected as an MLB All-Star, won one Gold Glove and two Silver Slugger awards, and was a World Series champion with the 2019 Nationals.

Until late in his senior year, James Madison, Charlotte, and UNC Wilmington were the only Division I programs to show interest in him.

In his final collegiate season, Zimmerman led the Cavaliers with a .393 average, .581 slugging percentage, 136 total bases, 92 hits, 59 RBIs, and 51 runs.

Through August 2011, he was one of 29 former UVA players to have made it to the major leagues, along with Michael Schwimer, Javier López, and Mark Reynolds.

[8] Zimmerman's collegiate awards and honors include 2005 All-American by Baseball America, 2005 All-American by National Collegiate Baseball Writers Association, 2005 All-ACC selection, 2005 ACC All-Tournament, Team and 2005 Virginia College Sports Information Directors (VaSID) Player of the Year.

[9] Zimmerman's .468 batting average set a national team single-season record and helped him earn the World University Championship tournament MVP.

Zimmerman also shared third base duties with Vinny Castilla, taking over the position on a more permanent basis between the time the Nationals were mathematically eliminated from playoff contention and the end of the season.

He remained with the Major League club to start the 2006 campaign, taking over third base duties from Castilla, who was traded to the San Diego Padres.

On April 5, 2006, he hit his first Major League home run off a 93-mph fastball in the ninth inning against Mets' closer Billy Wagner.

The usually stoic Zimmerman gleefully tossed his batting helmet in the air while rounding third and leaped onto home plate as his teammates crowded around him.

On September 27, 2006, against the Philadelphia Phillies, Zimmerman hit his 20th home run of the season and tied the Expos/Nationals franchise record for home runs by a rookie, set by Brad Wilkerson for the then-Expos in 2002 During his first season as the Nationals' third baseman, Zimmerman became a hometown hero and a fan favorite through his defense and ability to come through in late-inning situations.

Along with those two figures, he finished the 2006 season with 156 games played, 612 at-bats, .288 batting average, .352 OBP, 84 runs scored, 176 hits, 47 doubles, 3 triples, and 11 steals.

The one-run home run would have been considered routine had it not continued a trend that led to Zimmerman being declared a "human fireworks" show by an ESPN.com article.

"[15] On August 3, 2007, Zimmerman delivered his sixth walk-off game-winner in his first two seasons with a single to left, giving the Nationals a 3–2 win over the visiting St. Louis Cardinals.

Manager Manny Acta stated, "He has done some dramatic stuff since he's been up here...he doesn't get rattled when that situation comes up, and I think that's what he has shown here the last two years.

[17] On August 4, 2007, Zimmerman had his first career multi-homer day, hitting a solo shot in the fourth and a two-run homer in the sixth in a 12–1 victory over the St. Louis Cardinals.

In November 2007 during the offseason Zimmerman participated in a homerun derby fundraiser for Grassfield High School in Chesapeake, Virginia.

In that game, with two outs in the bottom of the ninth, Zimmerman hit a walk-off home run off of the Braves' Peter Moylan, giving the Nationals a 3–2 win.

[24] Zimmerman hit his 100th career home run on May 30, 2010, at Petco Park, becoming the second player to reach this milestone from the 2005 draft class.

[28] He received a cortisone injection on June 24 to mitigate the pain,[29] with apparent results: in his next 25 games, he hit .392 with 11 home runs and 28 RBI.

[33] Zimmerman, playing left field, caught the final out to what as at the time the longest game by innings in Nationals history.

[41] On July 27, Zimmerman hit the fourth consecutive home run by Nationals hitters off Milwaukee Brewers starter Michael Blazek, the first time the feat had been accomplished in Major League Baseball since the 2011 season.

Zimmerman ended the regular season with a career high 36 homers, with 108 RBI and a .303 batting average over 144 games played.

However, the Nationals lost the series to the defending champion Chicago Cubs in 5 games and were eliminated in the NLDS for the 4th time in a 6 year span.

[46] On July 5, 2019, Zimmerman hit his 1000th career RBI with a 7th inning double off of Kevin McCarthy against the Kansas City Royals.

[49] In the 2019 National League Division Series against the Los Angeles Dodgers, Zimmerman hit a 3-run home run in Game 4 that extended a 1-run lead and secured the win.

[62] Zimmerman would ultimately start at first base on October 3, the final game of the season; he was then removed in the 8th inning, receiving a standing ovation from the crowd at Nationals Park.

[64] He retired as the franchise (both the Nationals and Expos) all-time leader in many statistical categories including hits (1,846), home runs (284), RBI (1,061), and games played (1,799).

[71] Zimmerman has cited his mother's condition as a substantial formative influence on his development, saying that it forced him to grow up and assume responsibilities at an earlier age than most children.

[79] On January 5, 2016, it was announced that Zimmerman had filed a lawsuit suing Al Jazeera for defamation following the publication's release of the documentary "The Dark Side: Secrets of the Sports Dopers", which linked Zimmerman and Philadelphia Phillies first baseman Ryan Howard, among others, to a clinic that allegedly distributed steroids and HGH.