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.
Prior to the weekend's action, Audax Italiano were the other unbeaten club but they fell to a 4-3 home loss to Antofagasta.
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.
