The Tigers outscored the Razorbacks 42-26 in the second half after the game was tied 28-28 at halftime.
"The second half, we couldn't make any shots, and when you don't make many shots, it's hard to manufacture some with your defense," Arkansas coach Mike Anderson said. "I thought their strength really came to fruition in terms of rebounding the basketball. I thought Johnny O'Bryant controlled the boards, especially in the second half.
LSU (18-13) used a 10-2 run to take control of the game after halftime and led by as many as 17 points. Five Tigers players scored in double-figures, led by O'Bryant, who repeatedly got second-chance opportunities on the offensive end.
"In the second half he came out on the boards pretty tough," said Arkansas forward Michael Sanchez. "We just didn't respond. We got punched and we didn't respond."
Arkansas trailed for most of the game, briefly taking a 26-23 lead with 2:04 left in the first half. B.J. Young, who didn't score until late in the first half, led the Razorbacks with 13 points.
The 54 points were a season-low for the Razorbacks (18-14). Arkansas has now lost eight of its last 10 games and it appears the Razorbacks could miss out on the NIT later this month.
"I don't know whether we hit that wall or not," Anderson said. "I think some guys may have. That's why I think the energy, this time of the year it's got to be about the energy level. And you veteran guys got to be in charge."
LSU beat Arkansas for the second straight time, having also won 71-65 in Baton Rouge on Feb. 4. The Tigers won the season series between the teams 2-1.