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.
Union Espanola finished a distant third to the top two, 11 points back, after thrashing Cobresal 4-1 at home.
Diego Scotti, Sebastian Jaime, Lorenzo Faravelli and Francisco Castro all scored for the winners, who had life made easier for them after Alexis Salazar was dismissed for Cobresal seven minutes prior to the break.
A brace from Igor Lichnovsky helped Universidad Chile earn a point on the road at Cobreloa in a 2-2 draw, while Palestino dropped to fifth after losing 2-1 at home to Audax Italiano.
Universidad Concepcion and Deportes Iquique played out a 1-1 draw, with both sides reduced to nine men via dismissals.
Iquique were down to nine men and trailed 1-0, before Manuel Villalobos scored the equaliser with 19 minutes to play before Concepcion let their fury out at conceding as Alexis Machuca and Fernando Manriquez were red-carded.
Colo Colo struck twice in the opening quarter-hour to see off Nublense 2-0, ending the latter's three-match winning streak.
Antofagasta came from behind to earn a 1-1 draw at Santiago Wanderers, while Huachipato could not avoid finishing in last place in the Apertura phase despite a gritty 3-2 road win over Everton.
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