Sommer, who turns 38 in December, chose Belgium's Jupiler Pro League over a return home to Basel after leaving Inter as a free agent.
According to TuttoMercatoWeb, the Swiss goalkeeper turned down the chance to rejoin the club where he came through as a youngster and played until 2014, with the pull of one more season of Champions League football at the highest level proving too strong to resist. He is expected to put pen to paper on his Club Brugge contract this week.
Inter Milan marked his exit with a heartfelt tribute.
"Yann embraced the responsibility with the calm and composure always painted on his face, passing it on to his defence, the team, the stadium," the club said in a statement.
"Three years defending the Nerazzurri goal, three seasons in which his gloves were the foundation of Inter's runs, in which his class with his feet was a fundamental pillar of our build-up play. He bewitched us with his reflexes, with those instinctive, elegant dives that never left a hair out of place.
"15 clean sheets in 33 league appearances, closing out three unforgettable years in which he won two Scudetti, a Coppa Italia and an Italian Super Cup. 139 total appearances, keeping a clean sheet on 66 occasions: Yann Sommer has left an indelible mark on Inter's history. Thank you, Yann: it was wonderful to win together!"
While one era closes, Inter are working to secure another for the long term. The club is in talks over a new contract for Francesco Pio Esposito, the 2005-born striker who impressed in his debut senior season and has quickly become a symbol of Inter Milan's shift toward a younger squad under new head coach Cristian Chivu.
Negotiations are centred on extending his deal to 2031, a year beyond his current expiry, alongside a significant pay rise from his existing salary of around €1.2m per year.
Esposito's importance extends beyond club level too, with his form this season also shaping up to give him a prominent role in the new-look Italy squad taking shape in the coming weeks. Already a firm favourite with the San Siro crowd, the striker represents exactly the kind of homegrown certainty Inter's hierarchy want to build their future attack around.