Arndt beat Australians Simon Gerrans (Orica-Scott) and Cameron Meyer (Korda Mentha Real Estate Australia) at the end of the 173.9km race which started and finished in Geelong, Victoria.
Meyer had made a bold solo bid for victory with 600 metres to go Arndt reeled him in with a well-timed late sprint while holding off late charger Gerrans.
Arndt needed a helping hand over the steep Chalambra climb, where a late attack was expected, with his Dutch team mate Wilco Kelderman pacing him to the front of the peloton.
"I thought OK, if he (Kelderman) has done such a big pull, you also have to come back, you cannot give up," the 25-year-old Arndt told reporters.
"The last few days, we could also see some tennis matches (at the Australian Open) and they also said something like 'never give up, just focus and try again and try again'.
"That was actually a good motivation for today."
With the climbers unable to make significant ground on the inclines, the large leading group saw late attacks from Richie Porte (BMC), Nathan Haas (Dimension Data), Chris Froome (Sky) and Rafael Valls (Lotto-Soudal) before the sprinters moved into position in the final kilometre.
Tour Down Under winner Porte finished 21st and three-times Tour de France champion Froome faded after a lone bid for victory and crossed the line in 49th place in his first major race of the season.