In September 2011 Thomas began trialling with A-League club Melbourne Victory. On 15 September the club announced that he had signed a two-year contract. Thomas made his debut with Melbourne Victory as a player in the Round 5 clash with reigning premiers and champions Brisbane Roar at Etihad Stadium, coming on as a substitute after Victory first choice goalkeeper Ante Čović was sent off by referee Ben Williams for bringing down a Roar player in the Penalty area. He made an impressive debut, pulling off brilliant saves and helping Victory to a two all draw. Thomas made his second appearance in the Round 6 clash against A-League runners-up Central Coast, again putting up an impressive performance, pulling off brilliant saves and keeping a clean sheet in the Victory's nil-all draw. Thomas made his third appearance in the Round 1 clash against crosstown rivals Melbourne Heart. Despite putting up an impressive performance, and making several brilliant saves, the Victory went down 2–1 to the Heart, with goals coming from David Williams and Dylan Macallister. While Thomas improved, he would struggle to get regular game time, often being the second choice goal keeper behind Covic, Nathan Coe and later Danny Vukovic. A drop in form from Coe in the latter stages of the 2013/14 season would see Thomas get a chance to become the number one keeper but failed to grasp it, allowing Coe to be recalled back into the starting lineup. A year later a similar situation arose, however this time through a Coe injury. This time Thomas made the most of the opportunity, putting in consistently good performances, culminating in a very good albeit somewhat quiet game in the grand final against Sydney FC, to make it hard for Coe to return to the team as first choice keeper. Coe would depart the club at the off-season with most assuming that meant Thomas would be taking the number one goal keeping position. However, in a slightly surprising move, Melbourne Victory would sign Perth Glory 'keeper Danny Vukovic meaning that yet again, Thomas would have to settle for the back up 'keeping spot again. In the 2015/16 season, Vukovic would make a decent start to the season but then, against Brisbane Roar, would concede 5 goals, opening the door up again for Thomas to come in to the side again and wouldn't go out of the side for the rest of the year. Vukovic would depart for Sydney FC at the end of the season, which again most people thought that Thomas would become the number one 'keeper. This would finally happen with Victory signing a former backup 'keeper from the Central Coast Mariners as a back up for Thomas. In the 2016/17 season, Thomas would put in consistent performances, with the exception of the derby which ended in a 4–1 defeat. On 5 May 2018 Lawrence was named the best on ground in his team's 1–0 grand final win over Newcastle Jets, and he received the Joe Marston Medal. The Victory announced that Thomas had left the club to pursue overseas opportunities in July 2020.
Career statistics
CS = Clean Sheets 1 – includes A-League final series statistics
2 – AFC Champions League statistics are included in season commencing during group stages.
