On Tuesday, the defender sealed a season-long loan deal to the Rams - his third spell away from the Stamford Bridge.
The move saw Tomori reunite with Morris whom he worked with in the Blues youth setup; a successful relationship which yielded FA Youth Cup and UEFA Youth League champions titles.
In May, Morris left his role at Chelsea to link up with Frank Lampard at Derby, becoming the former England international's assistant coach.
“First of all, I am happy to be here – hopefully we can have a good year,” Tomori told RamsTV.
“I’m here to learn, I’m here to play games and I’m here to improve. I want to make the fans happy this year.
“I had some good years under Jody at Chelsea. We won the FA Youth Cup a few times, the youth Champions League, but overall, he’s just a good guy.
“I am excited to be linking back up with him for this year and, hopefully, we can enjoy some more good times together.
“He’s an intense guy, but that’s because he’s a winner. He wants to do well all the time and is very demanding when it comes to himself and working under him was a big factor in my decision to come here.”
The former saw him witness a team secure promotion to the English Premier League, while the latter; a successful battle to maintain Championship status.
“I came into the team at Brighton in January and at that time they were already flying," he continued.
“They had already gone close to promotion the year before and when I got there, everybody was just so focused on getting promotion. To be part of that was crazy really.
“Last year, I wanted to go out and play a bit more and I managed to do that at Hull last year. You learn different things in football. Last year was about fighting in games in order to get those results, trying to keep your head and stay calm in difficult circumstances.”
However, Tomori is keen on helping Derby go a step further. “It’s exciting times," he added.
“Last year, this club got to the playoffs and have come close to getting promoted a lot over the last few years.
“I’m here to be here and I’m happy to have this opportunity. Hopefully this year, we can go one better.”
Derby will look to build on their impressive start to the 2018-19 Championship campaign when they take on Leeds United at home on Saturday, and Tomori will hope to get some game time.