Hanson was born on August 28, 1986, in Tulsa, Oklahoma as the second child and only son in his family. After moving to California at a very young age, Hanson attended Redlands East Valley High School in Redlands, California, where he played baseball under coach Steve Hernandez. Hanson played catcher as a freshman, and first base the next year. He was placed on the mound in his junior season, and committed to Sacramento State University as a senior. Hanson graduated in June 2004, instead electing to continue his post-secondary education at Riverside Community College, where he was coached by Dennis Rogers. He played for the Corvallis Knights in the West Coast League, an independent summer collegiate baseball league. In 2005, he was selected in the 22nd round (677th overall pick) by the Atlanta Braves as a draft-and-follow pick.

The following year, in 2006, Hanson began playing for the Danville Braves of the Appalachian League. In Danville, he began the season as the league’s fourth-best prospect according to Baseball America. That season, Hanson ended up starting Game 2 of the Appalachian League Championship Series, finishing the season 4–1 with 56 strikeouts against nine walks. He also had a 2.09 earned run average (ERA) with a 0.99 walks plus hits per inning pitched (WHIP) ratio.

Before the 2007 season began, Hanson was named the best pitching prospect in the South Atlantic League and the ninth-best prospect in the Braves system. Hanson began the 2007 season in Class A, playing for the Rome Braves. When in Rome, Hanson amassed a 2–6 record with a 2.59 ERA in 14 starts (and one relief appearance). Midway through the season, Hanson was called up to the Myrtle Beach Pelicans, also a Class A team for the Atlanta Braves. He ended up finishing the season at 3–3 with a 4.20 ERA in 11 starts.

In the 2008 offseason, the Atlanta Braves were one of multiple teams that were interested in trading for San Diego Padres pitcher Jake Peavy. Hanson’s name was mentioned throughout the proceedings, but a trade for Peavy did not take place. He was considered by Baseball America to be the top prospect in the Braves’ farm system heading into the 2009 season. Hanson began the 2009 season with the Braves’ Triple-A affiliate, the Gwinnett Braves.

Hanson was called up by the Atlanta Braves on June 3, 2009 after the team cut Tom Glavine. He made his debut on June 7 against the Milwaukee Brewers, pitching 6 innings, striking out 5, giving up 6 earned runs, 3 home runs, and receiving a no decision. He gave up two home runs to Ryan Braun, the first being the first hit allowed in Hanson’s major league career.

Hanson was traded to the Angels in exchange for pitcher Jordan Walden on November 30, 2012. He played one season with the Angels, recording a 4–3 record with a 5.42 ERA in 15 appearances (13 starts) in 2013. He took a six-day bereavement leave in April after the death of his stepbrother. After returning and making two starts, he was granted a three-week personal leave to deal with what he described as his “mental issues with the death”. After the season, Hanson was non-tendered by the Angels, making him a free agent.

On February 11, 2014, Hanson agreed to a major league contract with the Texas Rangers. He was released on March 26.

On April 7, 2014, Hanson agreed to a minor league contract with the Chicago White Sox. He spent the season with the Charlotte Knights, who placed him on the DL on June 12 due to a shoulder injury, which caused him to miss the rest of the season.

Hanson agreed to a minor league contract with the San Francisco Giants on May 13, 2015. He was assigned to the San Jose Giants and was promoted to the Sacramento River Cats on July 5. He made eleven starts for Sacramento during the remainder of the season, pitching to a 3-5 record and a 5.60 ERA.

On November 9, 2015, Hanson died at Piedmont Hospital in Atlanta, after falling into a coma with catastrophic organ failure.

On December 11, 2015, a preliminary autopsy report was released, stating Hanson’s official cause of death was from “delayed complications of cocaine and alcohol toxicity”. The coroner ruled his death an accident caused by cocaine use.