The Time Trial leads into tomorrow's racing but carried separate world championship status with Olympic gold medallist Mariana Pajon (COL) repeating the elite women's Super Time Trial victory she won in Auckland two years ago, and 2011 World Champion Joris Daudet (FRA) won the men's Super Time Trial final.
Walker, who said she was unsure of her abilities against the best in the world after time away from the circuit, was fifth fastest in her first run in 36.627s to qualify for the Super Time Trial.
She went faster in the second run in 36.365s to displace her close friend Laura Smulders (NED) in the leader's chair before American Alise Post pipped her. After defending champion Caroline Buchanan (AUS) went slower and with only Pajon to follow, Walker knew she was on the podium.
"It's quite over-whelming. It's been such a long way back and I've had to go through so much, and had no idea how things were going to pan out so it was quite different to what I am used to," Walker said.
"Today I was really happy with two good laps and after a long time off racing.
"After everything I've gone through, I feel like this medal probably means the most to me of all the medals I've won," said the London Olympic silver medallist.
"What I did really well was to get really good track speed around the rest of the track but I know there are quite a few girls who finished behind me in the time trial who have really good first straight speed.
"Tomorrow I will need to be quite smart and quite patient and use my track speed to do as well as I can.