Phillips spent seven successful years at boyhood club Leeds United before deciding to take the next step in his career by joining Man City for a reported £42m in July 2022.
The 28-year-old had ambitions of establishing himself as a first-team regular under manager Pep Guardiola, but he was reduced to just five starts and 26 substitute outings in all competitions during his 18-month spell at the Etihad Stadium.
Phillips has since made the switch to West Ham on an initial loan deal with an option to buy in the summer, and the midfielder is excited to reignite his career under David Moyes.
"It's obviously a massive decision for me and my family, but I think it was a decision that I needed to make because I wasn't getting much game time," Phillips said in West Ham's official match programme for Sunday's Premier League clash against Arsenal.
"The one thing that I wanted when I left Man City in January was to be back playing and to be enjoying myself playing football as well.
"When you don't play football for so long, you kind of feel a little bit useless because you've not been doing anything. So, for me, it was just more coming to a good club with good fans and just enjoying my football again.
"I was very sad when I knew that my next step had to be to move on, but I got over that quite quickly and was just more excited than anything to get down here and see the place and see how London is, which is very busy. I was very excited to get going."
West Ham were keen to sign Phillips during his time at Leeds, but they ultimately lost out to Man City in the race for his signature two summers ago.
Phillips, who made his West Ham debut against Bournemouth earlier this month, has revealed that he was persuaded to make the move to the London Stadium this time around following conversations with sporting director Mark Noble and England international teammate Declan Rice, who left the Hammers to join Arsenal last summer.
"I know Dec quite well and I spoke to him about the club, and he spoke very highly, and he loves the club," said Phillips. "He just said, 'if there's a place you are going to go, go to West Ham because you'll love it there and have an amazing time because they've got great people'. I spoke to Nobes too and I can just tell by the way Nobes and Dec spoke about it that I'm going to like it here.
"There was obviously speculation two years ago and how for the past two years West Ham have wanted to sign me and I think the kind of person that I am, I kind of wanted to give David Moyes and myself the opportunity to try and work together for West Ham and hopefully we'll go on to do good things.
"I think we're climbing towards the Champions League spots as a club. I think, with the pedigree of the players that we have got and how well we've been performing, we're not going to drop below what they've done in the first half of the season. When everyone is fit, this team can cause anyone real problems."
Phillips added: "We've got very exciting wingers and very exciting strikers and forward players. I'm just here to do a defensive job and hopefully chip in with a few more goals.
"I look at myself and I'm a confident player and training with the best players in the world does rub off on you. I'm excited to get going and have a few games under my belt."
Phillips will be hoping to force his way back into Moyes's starting lineup when West Ham, who sit seventh in the Premier League table, play host to an Arsenal side that lost 2-0 to the Hammers at the Emirates Stadium earlier this season.