Henry, a 6-foot-9 senior, became the 33rd player in Ole Miss history to score 1,000 career points. He had one of his better games this season, making 7 of 12 shots from the field.
Ole Miss (16-12, 6-8 Southeastern Conference) never trailed, leading 34-24 at halftime before pulling away in the second half.
It was a crushing loss for LSU (17-11, 7-7), which had played its way into the NCAA Tournament conversation with a four-game winning streak. But the Tigers had a terrible offensive game, shooting just 31 percent (18 of 58) from the field.
The game was a stark contrast to the first meeting between the two teams on Jan. 7, when LSU drilled the Rebels 81-55 in Baton Rouge, La.
Ole Miss took the lead immediately on Henry's pull-up 3-pointer and never let up.
Henry had 13 first-half points, passing the 1,000-point mark on a pair of free throws. He's just the second Ole Miss player to have 1,000 career points and 100 career blocks.
Henry's had an up-and-down senior season, with some spectacular games mixed with virtual no-shows. But he played to his strengths against LSU, finishing with his left hand on drives to the basket and making open jumpers. He came into averaging a team-high 11.9 points.
Williams added 12 points in the first half, shooting 5 of 5 from the field, including two 3-pointers.
Ole Miss kept rolling in the second half. The Rebels stretched their lead to 43-26 on a short jumper by Williams with 13:04 remaining and were never threatened, rolling to a rare easy victory.
LSU coach Trent Johnson didn't see the end of it, receiving back-to-back technical fouls with 7:17 remaining. Ole Miss hit three of the four free throws assessed after the two technical to push its lead to 55-34.
LSU is used to playing low-scoring games, winning each of its previous four games with scores in the 60s. But the Tigers couldn't get into any sort of offensive rhythm against the Rebels' suffocating half-court defense.
LSU's leading scorer Justin Hamilton -- who was averaging 13.6 points per game -- didn't score until late in the second half when the game was already decided. He finished with two points and six rebounds.
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