The Steelmen, who finished 11th in the league, beat Championship side Rangers 6-1 on aggregate in the play-off final to confirm their safety.
The convincing victory signalled the green light for the 21-year-old left-back to sign a two-year deal for the Fir Park club, following his release by Celtic where injuries played a part in restricting him to just three appearances.
Although top-flight football was not a potential deal-breaker for the player who has played for Scotland at age levels from under-16 up to under-21, he was glad to see Ian Baraclough’s side survive and for the Well boss to confirm him as his first summer signing, after cutting 16 players.
Chalmers said: “I knew Celtic were going to release me and I spoke to a few clubs.
“Motherwell showed interest and with them being in the play-off, I got the chance to come in to train for a couple of days and the manager was happy with what I did.
“They were waiting to see where they were going to be and luckily they came through the play-off and everything worked out so I was delighted.
“It wasn’t a big issue (Premiership status). I just want to play games.
“I would obviously have preferred that they stayed up because that’s where I want to test myself, that’s where I feel I belong so I was delighted they stayed up.
“But if they went down this (move) still could have happened, you just never know.”
Chalmers “loved every minute” of his time at Celtic where he came through the youth academy but knew that for the sake of his career it was time to move on.
“I wouldn’t change my time at Celtic for anything,” said the defender, who had a loan spell at Falkirk in 2014.
“It was tough to leave Celtic. From the football side it wasn’t as hard as I felt it was the right time to move on.
“But with the amount of good people and the amount of friends I made it was hard.
“But I am 21 now and I just felt it was the right time for me to move on.
“I just want to play first-team football so I can’t wait to get started.
“In the last two seasons I have only played a couple of months’ football.
“Just as I had played a couple of games and (was) starting to break in and training with the first-team squad every day, I was really unfortunate with injuries.
“I was just unfortunate, it was nobody’s fault. These things happen.”
Chalmers, however, is well aware that he will have to oust 33-year-old Stevie Hammell, a Motherwell institution, from the left-back spot.
He said: “I know how good a player Stevie Hammell is, he showed over the two legs against Rangers that he still has a lot to offer.
“I am coming here to work hard and there are no guarantees that I will play.
“But I will do my best, work hard and hopefully I can force my way into the team.”