The Hungarian powered to a dominant victory in the 400m individual medley.
Hungary's "Iron Lady" of swimming, a treble gold medalist at the Rio Games in August, on Tuesday powered to a dominant victory in the 400m individual medley.
Her time of 4min 21.67sec was more than two seconds off her own world record, but it was comfortably in front of runner-up Ella Eastin's 4:27.74.
Easton seized silver after Vietnam's Anh Vien Nguyen appeared to touch second but was disqualified. American Madisyn Cox was third in 4:27.78.
The triumph came shortly after Italian veteran Federica Pellegrini denied Hosszu in the 200m freestyle.
Pellegrini, 28, was closing at the final turn and churned past Hosszu on the final lap to take the first short course world title of her career in 1:51.73.
Hosszu settled for silver in 1:52.28, with 16-year-old Canadian Taylor Ruck third in a national record of 1:52.50.
Hosszu, one of the few Rio stars competing in Windsor, pulled triple duty on Tuesday, also booking her place in the 100m backstroke final.
While Hosszu's win was an extension of a stellar year that saw her win 200m and 400m medley and 100m backstroke gold in Rio, South Korean Park Tae-Hwan's 400m freestyle triumph was a turnaround in a largely forgettable 2016.
Park, a 2008 Olympic gold medalist who fizzled in Rio after serving a drugs ban, pounced to overtake Russian Aleksandr Krasnykh in the final 100m, winning in 3:34.59sec.
Krasnykh took silver in 3:35.30 while 2014 short course world champion Peter Bernek of Hungary was third in 3:37.65.
Park will be hoping his first short course world crown is a launching point for a new phase of his career as swimmers begin looking toward the 2020 Tokyo Olympics.
After serving an 18-month steroid ban, Park battled South Korean team officials for the chance to compete in Rio.
But once there he failed to advance from the heats in the 100m, 200m and 400m free and scratched from the 1500m free.
Park showed signs of a resurgence with four titles at the Asian championships in November -- but also revealed last month that his training for Rio was hampered by worries over threats by former vice sports minister Kim Chong that his determination to compete in the 2016 Games could see him cut off from access to corporate sponsorship.
Chad le Clos also shook off Rio disappointment with a victory in the 200m butterfly.
The South African was denied an Olympic title repeat in the 200m fly by US great Michael Phelps.
But a storming finish saw him repeat as short course world champion in 1:48.76 -- the third-fastest performance ever in a 25m pool.
American Tom Shields, swimming in lane eight, led at the 150m mark but finished second in 1:49.50. Japan's Daiya Seto was third in 1:49.97.
China's Rio bronze medalist Wang Shun won the men's 200m medley in 1:51.74, ahead of Germany's Philip Heintz (1:52.07) and Japan's Seto (1:52.89).
Vladimir Morozov's storming third leg powered Russia to a victory over defending champions France in the men's 4x100m freestyle relay.
Morozov took the Russians from third to first, and Popkov held on for the victory in 3:05.90 went into the water for the third leg on Russia's 400 free relay in third place, but he blasted a 45.42 split, by far the fastest in the field, and Aleksandr Popkov held on to give the Russians the gold.
Nikita Lobintsev, Mikhail Vekovishchev, Morozov and Popkov combined to post a time of 3:05.90, with France second in 3:07.35. The United States and Australia shared bronze in 3:07.76.
The United States' quartet of Amanda Weir, Kelsi Worrell, Madison Kennedy and Mallory Comerford won the women's 4x100m free in 3:28.82 ahead of an Italian squad anchored by Pellegrini (3:30.28) and the Netherlands (3:31.10).