On 16th of December 2006, Andrew got married to Kelly Hansch. He also dated her for several years before getting married in 2006. As a married couple, they have already welcomed one child together.
Andrew received his formal education from Cassingham Elementary School. When he was in his 4th grade, he lost his maternal uncle. He was an artist and Andrew was inspired to follow his path. He became interested in music and began playing piano. Later he got enrolled at Dana Hills High School and he finally graduated from there in 2000. In 1997, he formed his first band, Left Here. They also won a local battle of the bands competition within short period of time but this band was disbanded. Later he released his eponymous four-track demo CD Andrew McMahon. In 1998, he formed the band piano rock band Something Corporate. Their debut album Ready... Break was released at the end of 2000. His net worth is said to be around $7 million dollars.