After purchasing the NBA's Trail Blazers in 1988, Allen bought the Seahawks in 1996 from Ken Behring, who was threatening to move the team to Southern California.
He had been suffering from non-Hodgkin's lymphoma, and passed away on Monday, his investment firm said.
Allen never married and had no children. In 1972, while in high school, the pair launched Traf-o-Data, a software company that tracked and analysed traffic patterns. Eventually Mr. Allen would drop out of Washington State University to work as a programmer, and then convince Bill Gates to drop out of Harvard in order to establish Microsoft.
His stake in Microsoft, having left him a billionaire many times over, allowed him to give back to his hometown of Seattle, and to its inhabitants. The name "Micro-Soft" for their joint venture was Allen's idea. In 1980, Microsoft was chosen by IBM to develop DOS for its new PC. Allen departed in 1983 amid tensions with Gates and after being diagnosed with cancer. He remained on the company's board of directors until 2000. Allen had looked for the ship for more than 8 years with the hopes that finding its final resting place would bring peace to the families who lost loved ones in its final battle.
Allen was also a skilled electric guitar player, performing with his band the Underthinkers. As a guitarist, he fronted a band called The Underthinkers, and wrote or cowrote every song on their 2013 album.
Lymphomas are cancers that attack the lymphatic system.
"My brother was a remarkable individual on every level", Paul's sister, Jody, said in a statement.
What people said about him:"It is with deep sadness that we announce the death of Paul Allen, our founder and noted technologist, philanthropist, community builder, conservationist, musician and supporter of the arts".