The 154km battle was whittled down to all the main contenders on the final city circuit and it was impossible to predict the outcome as the riders entered the final kilometre.
But it was Kopecky who emerged from the bunch sprint to cross the line to make it back-to-back victories after she triumphed in Glasgow last year.
American Chloe Dygert took the silver medal with Italian Elisa Longo-Borghini finishing in third place.
It continued a stunning year for the 28-year-old who won the UAE Tour and Tour of Britain, was second in the Giro and also triumphed in Paris-Roubaix and Strade Bianche.
She missed out on gold in the Olympics road race, finishing third, but would not be denied in Zurich.
"It was a really annoying day because it was raining and it wasn't warm, but on the climbs, it was warm and then in the downhill, you got so cold and I was freezing at the end," Kopecky said.
"I just tried to stay at my own pace and come back and in the end, it was just a lot of mind games."
Three-time world champion Marianne Vos looked in contention for victory as they started the final circuit before compatriot Demi Vollering began to wind up the pace on the climbs.
With 3km remaining it appeared to be between Kopecky, her SD Worx-Protime teammate Vollering, Longo-Borghini and Germany's Liane Lippert. But Dygert and Australia's Ruby Roseman-Gannon powered back into contention.
Vollering, who was runner-up to Kopecky last year, made the first move before Longo-Borghini took it on. But Kopecky simply had too much power as she roared to victory.
She is the first rider to win back-to-back women's titles since Vos in 2012-2013 and afterwards paid tribute to Swiss junior Muriel Furrer who died on Friday from injuries sustained in a crash in the junior women's road race.
"There's a kind of disbelief, but first of all I want to pay my condolences to the family of Muriel," Kopecky said.
"I think the minute of silence at the start, seeing the Swiss riders crying, is something you just don't want to see. I think it's a very hard moment for them as well."