Veterans Mark Naden (46 runs) and Richard Briant (32) put on 48 for the second wicket before Briant was stumped by wicketkeeper David Situ off the bowling of Horouta captain Clarence Campbell.
Daryl Dunn hit eight fours and a six in his innings of 61, only to be dismissed on the last ball of the innings by Horouta paceman Vaughan Thompson.
With Campion having made 186-5, Horouta lost wickets early to be 45-3.
Martin and Balat took the score to 138 before the introduction of Matt King to the attack brought about the dismissal of Balat for 31.
Campion, missing 6ft 5in paceman Max Briant with a broken arm, didn’t have the firepower required, and Martin brought up the winning runs in the 19th over.
This victory put Horouta on top of the Hope Cup standings going into the Christmas break. The competition resumes in mid-January.
Horouta captain Clarence Campbell was ecstatic with the result.
“It was an all-round performance as our bowlers restricted the Campion total and our batters did the job to get us home,” he said.
In the other game, Bollywood Stars High School Old Boys Presidents, 103, beat OBR (2), 92-9, by 11 runs.
Campion College 186-5 (D Dunn 61, M Naden 42, R Briant 36; C Campbell 2-31, V Thompson 2-31) Coastal Ultrasound Horouta 187-4 (K Martin 109 not out, T Balat 31; B Marshall 2-34). Horouta won by six wickets.