The scarce information available on fin whales (Balaenoptera physalus) in the Central Mediterranean Sea limits the understanding of key bio-ecological activities of the endangered Mediterranean population. This work is part of a collaborative effort within the project “KNOWhale” and aims to expand knowledge about the species’ acoustic behavior and seasonal distribution. Acoustic data were collected from three different recording areas. Site-1, located in the Ionian Sea: OBS/H, 2065 m depth, 100 Hz sampling frequency (fs), operating continuously between May 2017 - January 2018; Site-2, South Adriatic Sea (EMSO-ERIC regional facility): Silence-LP recorder, 700 m depth, 64 kHz fs, 50% duty cycle, November 2022 – June 2023; Site-3, Sicily Channel: SoundTrap ST600 recorder, 157 m depth, 192 kHz fs, 50% duty cycle, February - April 2022. Fin whales 20Hz calls were detected at all sites using custom automatic detector, with calls occurring in 17, 122 and 16.54 hours respectively in Site-1 (0,29% detection rate), Site-2 (4,35% detection rate), and Site-3 (2.14% detection rate). Our results show for the first time the acoustic presence of fin whales in the Adriatic Sea over several months and attest to their monthly occurrence in data-deficient regions. This work provides essential baseline knowledge for conservation purposes in the Central Mediterranean Sea.