The hosts were given their first real test of the tournament on Saturday (Sunday AEST) by an aggressive French side, but they ultimately came through with five tries to win 35-17 and set up the Twickenham decider.
Returning from an enforced absence in their quarter-final victory over Scotland due to concussion, Kildunne wasted little time making her mark against France, racing clear down the left wing before cutting inside and finishing between the posts to score England's first try after five minutes.
With England leading 21-12 with a little over 10 minutes to go, the 26-year-old scored her second with another stunning run, ducking inside and racing diagonally across the pitch to the line, leaving several French chasers in her wake.
Her performance earned her the player-of-the-match award and some well-deserved words of praise from England coach, the former All Blacks mentor John Mitchell.
"She's special, isn't she?" he told reporters at Ashton Gate.
"She deserves her accolades as last year's World Player of the Year. She's still very, very young.
"Everyone puts her on a poster. Everyone's superstar, but she's a very humble girl... She's not a woman that you box.
"She's dealing with life very well because she's put on a pedestal, and it's quite new to her in her life.
"So it's really important that we support her in that space, but also allow her to chase her goals."
Captain Zoe Aldcroft was equally effusive and knew there was going to be no stopping Kildunne when she set off on her sprint to the line for her second try.
"Ellie is absolutely electric; she can make something out of nothing," she said.
"And yeah, it's just about trying to keep behind her, but there's no doubt that she was going to keep going and get over that line. She was fantastic this evening."
With a week to go before England, chasing a third World Cup title, face Canada in Saturday's (Sunday AEST) decider at Twickenham, there was a possible cloud on the horizon with Kildunne seeming in discomfort in the closing stages of Saturday's encounter.
Mitchell said he did not know the extent of any potential injury for England's superstar fullback.
"Really not sure. It is pretty early, so, fingers crossed," he said.
