Martin Lasarte's men needed all three points to ensure they were not overtaken by O'Higgins (both 39 points) - with both sides sewing up victories late on Sunday - as Catolica topped the table at the end of the Apertura phase in the Chile Primera Division thanks to a superior goal difference.
The league leaders wrapped up victory when Ismael Sosa doubled their advantage on 90 minutes, after Jose Munoz opened the scoring on 67 minutes.
That meant O'Higgins' late heroics to come from behind to beat nine-man Rangers 4-3 away from home were rendered obsolete, in terms of the Copa Libertadores spot.
O'Higgins twice arrested a deficit – leading 2-1 at half-time after conceding first, before then overturning a 3-2 deficit with 12 minutes to play as Osman Huerta and Pablo Calandria were both on target to earn them the bittersweet victory.
Calandria finished with a brace of penalties, while Rangers' Mauricio Gomez also netted a spot-kick earlier for the hosts - and that was not the end of referee Patricio Polic's involvement in proceedings.
Polic sent off Rangers' Sebastian Luna and Nicolas Peric in the final 10 minutes, and O'Higgins capitalised via Calandria's second penalty to get the three points.
Colo Colo struck twice in the opening quarter-hour to see off Nublense 2-0, ending the latter's three-match winning streak.
