"Paul's family and friends were blessed to experience his wit, warmth, his generosity and deep concern," Allen's sister Jody said in a statement. "At this time of loss and grief for us—and so many others—we are profoundly grateful for the care and concern he demonstrated every day."
Allen announced he had non-Hodgkin's lymphoma on Oct. 1.
The Trail Blazers were Allen's first professional sports franchise that he owned, purchasing them in 1988. Allen bought the Seahawks in 1996. Seattle has reached the Super Bowl three times since then, and the team won Super Bowl XLVIII.
Allen purchased the MLS's Seattle Sounders in 2009. They currently share CenturyLink Field with the Seahawks.
Allen co-founded Microsoft with Bill Gates in 1975. He also developed a string of other businesses and philanthropies, including the Allen Institute for Brain Science.