The winger did it all with Celtic, winning the ‘treble-treble’ in Scotland as well as putting individual awards in the trophy cabinet.
But when game time dried up for him in the first half of this season, Sinclair decided to seek pastures new.
PNE offered him a new home, following up the interest they had shown last summer.
So after starting the week as a Celtic player training in the Dubai sunshine, Sinclair will end it in a North End shirt playing against local rivals Blackburn Rovers at Ewood Park.
Sinclair said: “A move this month was always going to be the right thing.
“I’m not at my happiest when I’m not playing football and scoring goals.
“I’d got to the stage where my game time was limited at Celtic so it was time to move on.
“I’ve joined a great club – the way it is going I think we can push on.
“When I spoke with Alex Neil about the move he was straightforward about it.
“He went straight in about how he works, the team here, the tactics, how he plays and what he expects from the team and from individuals.
“The manager was straight to the point and I liked what I heard.
“I’ve left a fantastic club in Celtic.
“The fans sang that amazing song for me and I had a great relationship with them.
“All the support they showed me in my three-and-a-half years there I’m truly thankful for.
“The big thing I learned during my time at Cletic was knowing how to win games every week.
“It was about winning there, that is what the expectation was every week. That helped me develop as a player.”
Sinclair made only seven appearances for Celtic’s first team this season.
But in his previous three campaigns he had been a regular fixture in the side.
Brendan Rodgers, who had managed him at Swansea, took him to Glasgow in August 2016.
Trophy after trophy came their way, Sinclair netting 62 goals for them in all competitions.
“I think it was the best part of my career, we were winning everything up there,” said Sinclair.
“Celtic won the treble-treble, I was voted player of the year and sports writers’ player of year.
“Brendan Rodgers left, there were a few changes and Lenny (Neil Lennon) came in.
“He is doing a great job and I’m sure they will get nine in a row.
“For me it is time to kick on and bring my form here to Preston, try to hit the ground running.
“It is a fresh start and a new chapter, a chance to play football and enjoy it again.
“I’ve played in the Championship before and know what it is about. It is relentless with so many games in the season.
“We’ve got some great players here and we need to keep pushing forward as a club.
“I’m on board to try and help the team push on.”
The timescale of the deal being done was slightly longer than it might have been, purely due to Celtic jetting off to Dubai for a training camp during the winter shutdown in Scotland.
Sinclair trained while the deal was put together back in the UK.
Then came the call to fly home and get the move over the line.
“There were worse places to be than Dubai while it was all going on,” said Sinclair with a smile.
“I knew there was a good chance that I would get a phone call to fly back at some point.
“That call came and it was a case of getting on the flight back.”
Sinclair trained for the first time with his Preston team-mates on Thursday morning. As long as international clearance comes through, he can expect to make his debut against Blackburn.
Whether that be from the start or as a substitute, North End manager Alex Neil would not reveal.
In the main he played on the left-hand side of the attack at Celtic, cutting inside on to his right foot.
That is something Callum Robinson used to do at PNE before his move to Sheffield United.
It has taken until now to properly replace him and Sinclair is certainly a player along the same lines as Robinson.
He can play centrally too, something he did on occasions for Celtic.
Neil thinks he can play right across the front, that versatility something he likes in his forwards.
Away from the pitch, Sinclair’s partner is a well-known face on television.
For many years, Helen Flanagan walked the cobbles of Coronation Street as Rosie Webster.
The couple have two daughters and they will be looking to settle back in the North West.