The Australian, who currently tops the rankings, made the best of challenging conditions to post an 8.50 on her way to a heat total of 16.70 to comfortably see off replacement surfer Melanie Bartels.
“I was pretty worried going into that heat because the waves were just so minimal,” Gilmore said.
“Performance-wise, when it’s inconsistent and very hard to surf, there are so many things going through your mind. It was really nerve-wracking, especially going against Mel Bartels, she’s one of my favourite surfers and I was nervous.”
Gilmore had to surf round two after a surprise defeat in round one against Alessa Quizon and the 24-year-old pointed to the tight take-off zone at Arpoador to explain her travails a day earlier.
“The girls really were hassling really hard yesterday,” Gilmore said. “When you’re sitting next to the rock you’re basically pushing each other on to that rock.
"It’s like a weird war out there and young Alessa (Quizon), it’s her first World Tour event, I think and I was still pretty jet-lagged after that first one.”
Another big name to hit back from a disappointing opening to the tournament was Coco Ho, the Hawaiian posting the day's highest single wave score of 8.57 on her way to a total of 16.57 and victory over Kiwi Sarah Mason.
“Aproador is pretty fun when there are waves, it was just inconsistent and scary for a heat,” Ho said. “I got my two, so I’m really stoked. I’m really happy that I just got to surf, because in my Round 1 heat, I didn’t even get to surf.”
Australia's Sally Fitzgibbons also won through to the next round as the 2011 runner-up in Rio beat Jacqueline Silva.
“Conditions today are a little bit tricky, but everyone’s on the same boat,” Fitzgibbons said. “It’s tough when you get hard conditions like we have this week, but the weather’s nice and there are people down here supporting me all the way down here in Brazil. I just hope there is a little pulse in the next round.”
Heat 1: Pauline Ado (FRA) 10.00 def. Paige Hareb (NZL) 8.17
Heat 2: Laura Enever (AUS) 12.96 def. Sage Erickson (USA) 12.23
Heat 3: Stephanie Gilmore (AUS) 16.70 def. Melanie Bartels (HAW)
Heat 4: Sally Fitzgibbons (AUS) 12.60 def. Jacqueline Silva (BRA) 5.30
Heat 5: Courtney Conlogue (USA) 14.17 def. Justine Dupont (FRA) 10.47
Heat 6: Coco Ho (HAW) 16.57 def. Sarah Mason (NZL) 10.00
Heat 1: Tyler Wright (AUS), Courtney Conlogue (USA), Alessa Quizon (HAW)
Heat 2: Stephanie Gilmore (AUS), Lakey Peterson (USA), Coco Ho (HAW)
Heat 3: Sally Fitzgibbons (AUS), Malia Manuel (HAW), Rebecca Woods (AUS)
Heat 4: Carissa Moore (HAW), Laura Enever (AUS), Pauline Ado (FRA)