The Swiss goalkeeper, who has won the Serie A title and Coppa Italia under Chivu's management this season, described his time in the city as personally and professionally enriching.
"So much, both on a human level and sporting level," Sommer said of his three seasons at the club.
"I have had fantastic experiences inside and outside the stadium. San Siro gives you indescribable emotions, the fans welcomed me with immense enthusiasm. And Milan is beautiful, with fantastic people and a deep culture."
He reflected on what he took from Inzaghi, under whom Inter Milan reached the Champions League final in 2025.
"Inzaghi brought a lot of emotion to the pitch but at the same time is a calm person in daily life. With him I learned to think big, to put in passion, to give everything to win — and I improved a lot with the ball at my feet."
On Chivu, who replaced Inzaghi last summer and led Inter to the domestic double in his debut season, Sommer's assessment was immediate.
"In the year with Chivu I felt comfortable straight away from a personal point of view. He is very serene and knows how to face high-level challenges in a relaxed manner."
Asked for three adjectives to describe Chivu, the 36-year-old goalkeeper offered a precise answer.
"Focused on objectives, professional, and collegial — in the sense of collaborative."
Chivu, the former Inter defender, took over after Inzaghi's departure to Al-Hilal and has since signed a contract extension through 2028.