Italy striker Belotti joined Roma on August 28th as a free agent following seven seasons at Serie A side Torino, after his contract with the club ended.
"I was not looking for a contract, I was looking for the right setting and situation for me," Belotti told a news conference on Thursday.
"I thought Roma was that opportunity."
Belotti, however, remained ready for when that opportunity would arrive, as he hired a personal trainer during the summer to maintain his fitness.
"(I wanted) to make sure I got in shape even if I wasn't taking part in a pre-season," he said.
"I think the fact (that) I played on Tuesday, even if only for 10 minutes, after just two training sessions shows that physically I am not far off."
The Italy international came on for striker Tammy Abraham (24) in the 80th minute of their home win over Monza, two days after he joined the club.
"It would have been great to cap it off with a goal - but it was an unforgettable evening for me," Belotti said.
Jose Mourinho's side are top of the table after four games on 10 points, while Atalanta and Torino - both on seven points - will play the last remaining game of the round on Thursday.