Asked in a media round after his first training session back with the club whether this would be his final campaign, the 40-year-old was candid: "Probably yes. But I might have thought that last year too.
"It could well be my last season. First I want to have a good year and, ideally, celebrate a little."
Dzeko rejoined training on Tuesday having signed terms that run through the 2026-27 season, extending his existing deal to 2027 with a reported salary of around €1.3m plus up to €400,000 in bonuses.
The striker turned down interest from Serie A, MLS and other Bundesliga clubs to stay put, choosing loyalty over a fresh start elsewhere.
"I had three other options, yes," Dzeko revealed. "I wanted to keep playing, but only for Schalke. I wouldn't have gone to another club."
He described an extensive round of conversations before making his decision: "I spoke to a lot of people. The coach, Max Lüftl, Youri Mulder, Frank Baumann, plenty of players. Of course I was convinced from the start about what I wanted to do.
"The plan was always for me to come back. In the end, thankfully, it worked out."
Dzeko joined Schalke on a free transfer from Fiorentina in January and became central to their promotion push, contributing nine goals and assists in eleven appearances during the second half of last season to help the club return to the Bundesliga.
He will continue to wear the number 10 shirt and arrives fresh from representing Bosnia and Herzegovina at this summer's World Cup, a tournament that briefly had him weighing retirement before deciding to press on for at least one more year.