Lawler turned professional in 1990. His first season proved to be quite successful as he reached the last 32 in the Dubai Classic, losing out 2–5 to former World Billiards Champion Rex Williams. He then followed this up with a run to the Quarter Finals of the Classic, beating John Virgo 5–3 to qualify, as well as Joe Johnson 5–3 in the second round, before losing 2–5 to Mike Hallett. His best run in a ranking tournament was in 1996, when he reached the final of the International Open, beating World Champion Stephen Hendry 5–3 in the second round, but his run ended in the final where he lost 9–3 to John Higgins.