Freshman pitcher Steven Bruce threw five innings of five-hit ball while the offense mounted a 6-2 lead.
After a wild pitch put OU (32-13) on the board and the Trojans tied the game on an unearned run in the second, the Sooners exploded for two runs in the third, one in the fourth and two in the fifth.
Ellison brought in his second run with a bunt single in the fourth, and the two runs in the fifth were plated on another RBI single by Seitzer and a sacrifice-bunt by sophomore second baseman Max White.
Seitzer went 2-for-4 with the two RBIs, and Ellison finished the game with two hits in three at-bats and drove in two runs.
Once Bruce, who struck out five en route to his second career victory, left the game, head coach Sunny Golloway used four pitchers to finish off the final four innings.
Arkansas-Little Rock added its final run on an RBI groundout in the eighth, and the Sooners responded with an unearned run in the ninth on a fielding error.
The run in the ninth erased the save situation, but senior closer Ryan Duke faced four batters to record the game's final three outs.
OU returns home for a three-game set with the Kansas Jayhawks starting at 6:30 p.m. Friday.