It took Martin Lasarte's league leaders until the hour-mark to crack second-bottom Huachipato, and their first two goals came from the penalty spot.
Milovan Mirosevic converted the first, before Nicolas Castillo doubled the advantage with his spot-kick.
Castillo finished with a brace, before Enzo Andia added Catolica's fourth as they boosted their already handy goal differential to plus 14.
Cobreloa remain the only other undefeated side in the league, as they kept in touch with Catolica courtesy of a 1-0 triumph at Union Espanola.
Jose Perez struck on 31 minutes, but the second-placed club were forced to hold on with 10 men in the second half when Rene Lima was dismissed with 23 minutes to play.
Prior to the weekend's action, Audax Italiano were the other unbeaten club but they fell to a 4-3 home loss to Antofagasta.
Audax are 11th, with one win and five draws to their name in seven matches.
O'Higgins bounced back from their first loss of the season at their last start, with a 1-0 home win over Nublense.
Pablo Calandria's seventh-minute goal ensured O'Higgins maintained third spot in the league, with Deportes Iquique (fourth), Cobresal (fifth), Everton (sixth) and Antofagasta (seventh) all winning.
Deportes had a 2-0 road win over Santiago Wanderers, while Cobresal struck early before holding onto a 1-0 home victory over Universidad de Concepcion.
Everton arrested an early deficit to beat Universidad Chile 2-1, while Colo Colo dismissed Rangers 3-0 on the road and Palestino equalised late in a 1-1 draw at home to Union La Calera.
