Arrington went 3-for-4 at the field with a two-run single in the fourth inning. O'Hearn was 3-for-5 with RBI singles in both the fifth and ninth innings.
The Bearkats trailed 2-0 after three innings but bounced back to score three runs in the fourth inning and two in the fifth, then add insurance runs in the eighth and ninth innings.
Justin Jackson (3-2) was the winning pitcher for the Bearkats, spreading nine hits over six and a third innings and striking out six Colonel batters.
The victory upped Sam Houston's season record to 10-8 and evened the Southland Conference series between the two teams at one victory apiece. The rubber game of the series will take place Sunday afternoon.
Nicholls dropped to 11-8 for the season. Both the Bearkats and the Colonels stand 3-2 in Southland Conference action.
Sam Houston will return home Tuesday to begin a six game home stand against the Baylor Bears in a 6:30 p.m. midweek game at Don Sanders Stadium.
The Bearkats play host to Texas State Friday through Sunday in their next Southland series March 23-25.