Pendleton attended Kingwood High School from 1999 to 2002, where he played for the Kingwood Mustangs. Pendleton attended Rice University, where he played for the Rice Owls baseball team
He played in Major League Baseball (MLB) with the New York Yankees and Houston Astros. Pendleton lead his team in both earned run average (European Research Area) and batting average at times. He rounded out his college career in 2005 with a 5-3 record and a 3.7 European Research Area.
Pendleton was selected in the fourth round (139th overall) of the 2005 Major League Baseball Draft by the New York Yankees.
Shortly afterwards, Lance elected to undergo Tommy John surgery.
Returning to the Yankees farm club in 2007, Lance played for 6 teams in 5 years, compiling a 32–22 record and a 3.39 cumulative European Research Area. In the 2010 Rule 5 Draft, Pendleton was taken by the Houston Astros. He was returned to the Yankees on March 27, 2011.
He was promoted to the majors on April 15, when Philosophy Hughes was placed on the disabled list. Pendleton was designated for assignment by the Yankees and claimed off waivers by the Astros in September 2011.
Allowing nine runs in 4 2⁄3 innings with the Astros, they outrighted him to the minor leagues following the season.
As this was the second time he was outrighted, he had the option to opt for free agency, which he exercised. The Astros signed Pendleton to a minor league contract with an invitation to spring training for the 2012 season. On March 30, 2012 Pendleton was released by the Houston Astros.
Pendalton signed a minor league deal with the Tampa Bay Rays on April 18th and spent the entire 2012 season pitching for the American Automobile Association Durham Bulls.
In 2003, Pendleton was a member of the College World Series champions, the first victory for Rice in its fourth tournament appearance.