Mourinho was shown the door seven months after leading the west London club to the title, after Chelsea opened their defence at the start of the 2015-16 season with nine defeats in their first 16 games.
At the time the club statement claimed the Portuguese had left by mutual consent but Mourinho, who returns to Stamford Bridge for the first time since with Manchester United on Sunday, was adamant he was dismissed by owner Roman Abramovich.
“Mr Abramovich decided to sack me,” He told Sky Sports. “It was not mutual consent. But I left without a bad word about anything or anyone at the club.
“That was in my first period at Chelsea when I agreed it was time to change.
“I was keen to change, more than ready to go to other countries but this time it was not like that.
“It was a decision by the owner and I was informed of that decision. I accepted it in a polite way and we signed the papers. I did it in a calm, respectful way.”
Mourinho continued to live in London before he was named United boss in May.
“I waited for what I preferred, which was to stay in England, in the Premier League and I was lucky to have a big club like Manchester United,” he added.
“It took a couple of days [to get over it] and then it was finished and I started my life in a common way.
“I was still in London, I kept a house there, I was walking in the street, going to the gym, watching football…”
Mourinho, who guided Chelsea to two Premier League titles in his first spell in charge, believes the sack is a part of modern management.
“It’s not nice for me or anyone but that’s life, I took it in a positive way,” he said.
“To be sacked is [part of] football, many of the best managers in the history of football have had their moment to be sacked.
“Of course there are exceptions but normally, and especially in modern football, you are in a position where it can happen to anyone.
“If it was a club where I gave nothing it would be more difficult. When I leave the club that in two different periods I gave titles and, to the fans, some of the best moments that a club’s supporters can have, then I leave with a feeling of ‘I did my job’.”
Mourinho claimed the fans wanted him to stay before the axe fell.
“I don’t think they wanted it but, even if they did, they cannot remove me from Chelsea history,” he said.
“I am in their history and they belong to my history too, so there is no reason for bad feelings.”