Thomas remained with Home Improvement well into his teenage years but left the show in 1998 to focus on academics, and was only involved in three episodes of the final season.

In early 2004, he had a small guest role on 8 Simple Rules for Dating My Teenage Daughter, another ABC sitcom, and appeared in the WB's Smallville in 2002 and 2004.

[8] On March 22, 2013, Thomas guest-starred on the second-season finale of his third ABC sitcom, Last Man Standing, and again in the fourth episode of the third season on October 11, 2013, reuniting with Tim Allen, his TV father from Home Improvement.

[9] On January 10, 2015, he had a small cameo on the twelfth episode of the fourth season of Last Man Standing, reuniting with both of his TV parents from Home Improvement, Tim Allen and Patricia Richardson.

Other live-action films starring Thomas are an adaptation of The Adventures of Pinocchio (in which he played and voiced the titular character), Wild America, Speedway Junky, and Walking Across Egypt.