Allen purchased the Portland Trail Blazers NBA team, fulfilling his childhood dream of owning a professional sports franchise. He remained the owner until his death.

Allen bought the Seattle Seahawks NFL team, preventing their relocation to Southern California. This act cemented his status as a local hero and a champion of Seattle sports.

Allen became an investor in Seattle Sounders FC, a Major League Soccer (MLS) team.

Allen's ownership of the Seahawks and Trail Blazers was marked by his commitment to the teams and their communities. He invested in facilities, supported charitable initiatives, and strived to bring championship success to Seattle and Portland.