Cleveland Browns drafted Thomas in the first round of the 2007 NFL Draft with the third overall selection. Thomas spent the draft fishing on Lake Michigan with his father, father-in-law, and Joe Panos, who was also a standout offensive lineman at Wisconsin and is a former Brookfield resident. Thomas discovered he was drafted by the Browns via cell phone. Thomas signed a six-year contract worth $43 million, $23 million guaranteed, including a voidable year, with the Browns. Thomas won the starting left tackle job, with previous Browns left tackle Kevin Shaffer moving to right tackle. He made his NFL debut versus the Pittsburgh Steelers in Week 1 and played every offensive snap for the Browns in 2007. Thomas quickly became one of the top-performing members of the 2007 draft class and was named the NFL's Rookie of the Month for November. Thomas was selected to the 2008 Pro Bowl, replacing Jason Peters of the Buffalo Bills. He was named to the NFL All-Rookie Team. Thomas came in second in the voting for NFL Rookie of the Year. He was the only player to receive votes besides the eventual winner, Adrian Peterson. 2008 season For the second consecutive season, Thomas started each game for the Browns. Thomas was selected to his second Pro Bowl. During the 2008 campaign, the Browns offensive line only allowed 19 sacks, which was tied for the third fewest in franchise history. Thomas played in every snap during the season, though the Browns finished the season with a 4–12 record. 2009 season Thomas continued his role as a reliable presence for the Browns' offensive line in the 2009 season. He started all 16 games in another Pro Bowl season. For the first time as a professional, Thomas was named as a First-team All-Pro. The Browns finished with a 5–11 record. 2010 season For the fourth consecutive season, Thomas started all 16 games for the Browns. However, the Browns once again finished with a 5–11 record. Thomas earned Pro Bowl and First-team All-Pro honors once again. He was ranked 43rd by his fellow players on the NFL Top 100 Players of 2011. 2011 season On August 22, 2011, Thomas and the Browns agreed to a record setting seven-year, $84 million extension with $44 million guaranteed. The deal was negotiated by his agent Peter Schaffer and Matt Thomas and Tom Heckert of the Browns. On December 27, 2011, Thomas