This study presents evidence of diel patterns in fin whale (Balaenoptera physalus) 20-Hz acoustic presence in Eastern Antarctic waters. Passive acoustic recordings were collected at four sites in Eastern Antarctic waters from 2013-2019. A generalised linear model (GLM) was used to test the null hypothesis that fin whale 20-Hz acoustic presence does not show significant variation between light regimes dawn, day, dusk, and night. In the Indian sector of Antarctica, at the Prydz and Southern Kerguelen Plateau sites, fin whale acoustic presence was significantly more common during the night and dawn before declining during the day and dusk. Whilst still significant, a variation to this diel pattern was observed in the Pacific sector, at the Dumont d’Urville site: Fin whale acoustic presence was significantly more common during the day than dusk and night. The identified diel patterns in the Indian sector of Eastern Antarctica correlate with previously identified diel patterns of the fin whales’ main prey. We suggest an indirect association between fin whale acoustic presence and foraging, with the animals more likely to produce the 20-Hz pulse during the night when not foraging and less likely to produce the 20-Hz pulse when foraging during the day.