The 2012 Campeonato Nacional Apertura Petrobras was the Chilean football top tier’s 90th season. Universidad de Chile was the tournament's champion, after beating O'Higgins on penalties, in the finals.
For all ties, the lower-seeded team play the first leg at home.
Updated as of games played on July 2, 2012.
Universidad de Chile wins final by PK 2-0.
In the quarterfinals, the 1 seed play the 8 seed, the 2 seed play the 7 seed, the 3 seed play the 6 seed, and the 4 seed play the 5 seed.
In the semifinals, the highest seed play the lowest seed, and the second-highest seed play the second-lowest seed.
Universidad de Chile won 4–2 on aggregate.
2–2 on aggregate. O'Higgins won on away goals rule.
3–3 on aggregate. Universidad de Chile won on penalties.