Thaddeus Young added 20 points on 6 of 9 shooting, and Jrue Holiday chipped in with 19 points for the 76ers (20-9).
Williams was averaging 19 points over the previous four games. He stayed hot Monday night, making several big shots including a 3-pointer with 6:11 remaining after the Bobcats had pulled within 71-69.
He also hit a 3-pointer in the final minute to seal Philadelphia's second straight win.
Corey Maggette scored a season-high 22 points for Charlotte, which fell to 3-25 on the season. It's the worst record in the NBA and drops the Bobcats' winning percentage below that of the 1972-73 76ers, who finished with the worst record ever in the NBA at 9-72.
Kemba Walker added 21 points and Reggie Williams chipped in with 14 for Charlotte.
The game took on a familiar theme early on for the Bobcats.
For the third straight game, they shot less than 34 percent from the field in the first quarter and found themselves behind by double digits. They had a similar start in two previous blowout losses to the Chicago Bulls and Los Angeles Clippers over the weekend.
It didn't turn out that way this time, though.
Holiday scored Philadelphia's first eight points of the game after hitting his first four shots from the field as the 76ers jumped out to a 28-17 lead. But the 76ers were not able to distance themselves from the Bobcats.
Despite having the second-best defense in the league - and facing the worst offense in the league - the 76ers couldn't put together a run in the second or third quarters. The Bobcats cut their lead to 69-67 late in the third quarter behind 18 points from Maggette.
However, the 76ers refused to surrender the lead.
The Bobcats again climbed to within two with 6:11 left in the game after back-to-back 3-pointers by Walker, but Williams knocked home a 3-pointer from the wing to quell the rally. The Bobcats never mounted a challenge after that as the 76ers outscored the Bobcats 18-10 down the stretch.
Once again, the Bobcats were dominated in the paint, where the 76ers scored 42 of their points.
Notes: Williams has come off the bench in every game this season and is leading the 76ers in scoring. The last player to lead his team in scoring for an entire season without making a single start was Dell Curry for the Charlotte Hornets in 1993-94. Curry is now a television color analyst for the Bobcats. ... Andre Iguodala came in shooting 40.2 percent from 3-point range this season but was 0 for 3 against the Bobcats.
