Erakovic, who came into the tournament ranked 85th and without a career championship, earned a 2-6, 7-5, 6-4 victory in a semifinal that took nearly 2 1/2 hours.
Paszek returned to Quebec City after winning her second career WTA singles title here last year as a qualifier, but thoughts of a repeat championship were erased Saturday.
This has been a remarkable climb up the rankings for Erakovic, who after a six-month break due to a left hip injury in 2009 saw her ranking fall to No. 750 (April 2010). She was ranked 333rd at the start of the 2011 season.
The 2011 Bell Challenge titlist will earn $37,000.