After law school, he clerked for Chief Justice Daniel L. Herrmann of the Supreme Court of Delaware.

Following his clerkship, he was in private practice in Wilmington, Delaware from 1976 to 2000 at the law firm of Richards, Layton & Finger.

Ambro serves as an adjunct professor at his alma mater, Georgetown University, where he teaches a course on public speaking to undergraduate students.

The Thomas L. Ambro Fellowship, awarded to support a summer internship with the United States Bankruptcy Court for the District of Delaware, is named in his honor.

[3] Ambro was nominated to the United States Court of Appeals for the Third Circuit by President Bill Clinton on September 29, 1999, to fill a seat vacated by Judge Walter K. Stapleton, who assumed senior status on June 2, 1999.