Smith made his MLB debut with the Colorado Rockies on September 16, 2007, in a 13–0 home win over the Florida Marlins.
 He did not record a hit in two total at bats during the game.
 He got his first hit, an infield single, on September 21, 2007, in a 2–1 extra-innings road win over the San Diego Padres.
 His hit came off of Doug Brocail in the top of the 12th inning.
 Smith played in seven games during the regular season, racking up five hits in eight at bats.

Smith's successful stint during the regular season earned him a spot on the Rockies' 2007 postseason roster.
In the 2007 National League Division Series against the Philadelphia Phillies, Smith had one pinch hit in two at bats.
His lone hit came in the second game of the series in a 10–5 win against the Phillies.
It was an infield hit in the top of the fourth inning that loaded the bases with the Rockies down, 3–2.
The next batter, Colorado second baseman Kazuo Matsui, went on to hit a memorable grand slam to give the Rockies a lead that they would never relinquish.
Colorado went on to sweep the Phillies in three games and then went on to sweep the Arizona Diamondbacks in four games in the 2007 National League Championship Series.
Once again, Smith had one pinch hit in two at bats.
The one hit was in the fourth game of the series in a 6–4 series-clinching win against the Diamondbacks.
This time, Smith hit a double that came with two outs and two runners in scoring position in the bottom of the fourth inning with the Rockies down, 1–0.
The double drove in both runners to give Colorado a 2–1 lead.
Smith then went on to score during the inning after a Matsui single.
Colorado left fielder Matt Holliday also hit a three-run home run in the fourth inning to cap off a six-run fourth inning, all with two outs.

Smith was the final out in the 2007 World Series, striking out against Boston Red Sox's closer Jonathan Papelbon.
In that postseason Smith excelled, hitting above .500.

Smith hit his first career home run, a three-run shot, on May 25, 2008, in a 4–1 home win over the New York Mets.
 He hit the home run off of John Maine in the bottom of the fourth inning.
Smith also hit his first career inside the park home run that season, which was the eighth in Colorado Rockies history.
Smith made his MLB debut with the Colorado Rockies on September 16, 2007, in a 13–0 home win over the Florida Marlins.  He did not record a hit in two total at bats during the game.  He got his first hit, an infield single, on September 21, 2007, in a 2–1 extra-innings road win over the San Diego Padres.  His hit came off of Doug Brocail in the top of the 12th inning.  Smith played in seven games during the regular season, racking up five hits in eight at bats.
Smith's successful stint during the regular season earned him a spot on the Rockies' 2007 postseason roster. In the 2007 National League Division Series against the Philadelphia Phillies, Smith had one pinch hit in two at bats. His lone hit came in the second game of the series in a 10–5 win against the Phillies. It was an infield hit in the top of the fourth inning that loaded the bases with the Rockies down, 3–2. The next batter, Colorado second baseman Kazuo Matsui, went on to hit a memorable grand slam to give the Rockies a lead that they would never relinquish. Colorado went on to sweep the Phillies in three games and then went on to sweep the Arizona Diamondbacks in four games in the 2007 National League Championship Series. Once again, Smith had one pinch hit in two at bats. The one hit was in the fourth game of the series in a 6–4 series-clinching win against the Diamondbacks. This time, Smith hit a double that came with two outs and two runners in scoring position in the bottom of the fourth inning with the Rockies down, 1–0. The double drove in both runners to give Colorado a 2–1 lead. Smith then went on to score during the inning after a Matsui single. Colorado left fielder Matt Holliday also hit a three-run home run in the fourth inning to cap off a six-run fourth inning, all with two outs.
Smith was the final out in the 2007 World Series, striking out against Boston Red Sox's closer Jonathan Papelbon. In that postseason Smith excelled, hitting above .500.
Smith hit his first career home run, a three-run shot, on May 25, 2008, in a 4–1 home win over the New York Mets.  He hit the home run off of John Maine in the bottom of the fourth inning. Smith also hit his first career inside the park home run that season, which was the eighth in Colorado Rockies history.
Seth Smith