Vos got the better of Elisa Longo Borghini (Trek-Segafredo) in the uphill finale, distancing her with 200 metres to go to the finish as the Italian champion was forced to settle for second with Anna van der Breggen (SD-Worx) coming in third to maintain her overall lead in the maglia rosa.
“It is an incredible number, but it is not really something I was thinking of," Vos said after the stage, sporting the pink jersey as the current leader in the points classification.
"You know, every day is a new day in the Giro, and every day you have to be ready to focus, to fight and to get there.
"My team is also inspirational, getting me in the right position and focussed to win again. It’s number two this Giro, the total is incredible."
The hilly 110 kilometre course with a five-lap finishing circuit around Puegnago del Garda saw an early attack on the first lap by Matilde Vitillo (BePink) and Riejanne Markus (Jumbo-Visma), the two gapping the peloton by up to a minute and 30 seconds before being reeled in prior to the start of the next section.
Lucinda Brand (Trek-Segafredo) was the next to go shortly after the second lap began, stretching out a similar time gap and holding it all the way until the final 30 kilometres when a chase group formed led by Eugenie Duval (FDJ Nouvelle-Aquitaine Futuroscope) with Sofia Bertizzolo (Liv Racing), Coryn Rivera (Team DSM), Alexis Ryan (Canyon-SRAM) and Leah Thomas (Movistar) also in pursuit.
The group managed to bridge across to Brand with 25 kilometres left, but were all caught by the peloton shortly after as SD Worx got in formation at the head of the race as they travelled over the top of the climb and into the penultimate lap with 16.8 kilometres to the finish.
After multiple short-lived attacks on the final lap, Trek-Segafredo, Ceratizit-WNT, Team DSM and Canyon-SRAM all set up their lead-out trains at the fore of a reduced peloton as the riders hit the climb towards the finish.
With 1.3 kilometres to go, Australian Tiffany Cromwell (Canyon-SRAM) saw her opportunity, launching a ferocious attack with Longo Borghini and Vos forced to chase as Rivera struggled to keep up.
Longo Borghini then mounted her own attack on Cromwell at the 1-kilometre mark, opening up a gap towards the end of the climb before Vos leapt off the Italian's wheel in the final 500 metres to make it win number 30 in her Giro Rosa career.
Watch the highlights from the Giro d'Italia Donne on SBS from 3:30pm weekends or 4pm weekdays (July 3-12) or available earlier via SBS On Demand and the Cycling Central website.