The No.3-seeded Safarova lost serve early in the first set but held all eight of her other service games, eventually defeating the No.6-seeded Erakovic in an hour and 29 minutes for the title, 64 63.
Safarova came away with her fifth WTA title, and first in more than five years - her first four WTA titles came at Estoril and Forest Hills in 2005, Gold Coast in 2006 and then Forest Hills again in 2008.
"It was just about a few points today, but I was more consistent with my game and more aggressive, and I think that's why I won," Safarova said. "My strategy was to try to go to her backhand side and just try to use my lefty shots as well as I could. I was a little bit nervous at the end because it was so long since my last WTA title - I really wanted to win the title today - so it's great I was able to do that."
Safarova was asked about the gap. "I hope it's not another five years until the next one!" she said.
The Czech is also the second lefty to win a WTA title in 2013, after Petra Kvitova, who won in Dubai.
Erakovic was playing the Québec City final for the second time - she was a runner-up here two years ago to Barbora Zahlavova Strycova. The New Zealander is now 1-3 in her career in WTA finals.
"I really tried hard to get things right, but Lucie made it very difficult for me today," Erakovic said after the match. "She played solid and didn't let up her lead at all. And I was struggling to find my rhythm with her lefty serve and in the rallies - so I just have to take my hat off to her and move on now.
"I played good tennis and made the finals here, so overall not too much to be disappointed about!"
"It wasn't an easy draw - they've been playing some really good tennis recently, and the last few years too - so we're really happy to win today," Rodionova said. "It was amazing to play against them in the final. We had a good plan before the match and implemented and executed that plan really well.
"We've been working a lot over the last few years to play more as a team, and less as individuals, and we really complemented each other well here in Québec. We really understand each other now."
Kudryavtseva and Rodionova won their second WTA doubles title together, having won Strasbourg three years ago. Kudryavtseva now has five WTA doubles titles to her name, while Rodionova has six.