Born in Belgium where his father was stationed while serving in the US Air Force. He moved to Chicago when he was 3 years old.
In 1991, he starred in the made-for-TV movie Backfield in Motion (1991) (TV), which co-starred the production team of Roseanne and Tom Arnold. The next year, Galecki joined the cast of "Roseanne" (1988) as Darlene's sensitive and put-upon boyfriend, David.
At the age of 11, he received a Joseph Jefferson citation nomination for his critically-acclaimed performance as John Henry in The Member of the Wedding.
By age 7, he began performing in such prestigious theater productions as "Fiddler on the Roof", "Pippin" and "Galileo", opposite Brian Dennehy at The Goodman Theater in Chicago.
Star/producer/writer Roseanne of "Roseanne" (1988) praises Galecki's "great vulnerability".
Brother of Nick Galecki.
Close friend of Sara Gilbert.
Has a sister, Allison Galecki.