After turning 50, Williams announced that he would participate in the 2010 PBA Senior Tour (called the PBA50 Tour since 2013), but in limited events due to Team USA and other obligations.
Williams made his PBA Senior Tour debut on May 3, 2010, at the Miller High Life Senior Classic in Mooresville, NC. To the surprise of no one, he won the tournament three days later. On June 18, 2010, Williams had a chance to become just the second bowler to win the USBC Masters and USBC Senior Masters in a career (joining Dave Soutar), and the first to win both in the same year. Williams made the three-game final, but he was denied the title when he fell, 705-628, to fellow PBA Hall of Famer Wayne Webb.
Although Pete Weber is frequently presented to the general public as the poster-boy of the PBA, Williams might be the most respected and popular player on tour. This is because of his cool, confident demeanor, and his unparalleled success over the last two decades. Williams's longevity is further evidenced by the fact that more than one-third of his 47 titles (17) and 6 of his 8 majors have come after he reached age 40. Williams' most recent title in the 2010 USBC Masters came after he reached age 50. In fact, Williams swept every major PBA statistical category in the 2009-10 season, leading the tour in earnings ($152,670), average (222.89), match play appearances (15), and overall competition points. (See PBA Bowling Tour: 2009-10 season.)
Williams was named "Male Bowler of the Decade" (2000–2009) in the Winter, 2010 issue of U.S. Bowler—an incredible accomplishment considering he started the decade at age 40. He won his unprecedented seventh PBA Player of the Year award in 2010, becoming the oldest player in history (50) to earn that honor.