The midfielder took a lead role on the pitch to help the Lilywhites to promotion from League One six years ago and then establish themselves in the Championship.
With more than 300 games for PNE, Gallagher has now put the match boots away to focus on coaching.
Some players choose to go down a different career path after finishing playing but for 36-year-old Gallagher it was always going to be coaching.
“Being a coach was something I had always wanted to do,” Gallagher told the Lancashire Post.
“When you get to the latter years of your career you start thinking and looking at what you’ll do next. You could probably see from the way I was playing in the last few years that I was playing like a coach or a manager on the pitch.
“I was trying to control the midfield and control the players around me.
“Doing that I felt a big sense of responsibility and now I’ve got this coaching role which I’m so grateful for.
“About 18 months ago, Alex Neil gave me the chance to coach the Under-16s.
“He also started to involve me at first-team level, inviting me into the coaching room for meetings and analysis.
“For the last eight games of the season I got the chance with Frankie McAvoy on the coaching team.
“I was delighted to take that opportunity and the results we got were excellent.”
When McAvoy landed the head coach role full-time at the start of last week, Gallagher was officially added to the coaching staff.
That is when he announced his retirement from playing although he hopes there can be a farewell game during the pre-season programme.
Gallagher reflects on the last eight games of the season with a sense of pride.
Led by McAvoy, North End won five, drew two and lost one, finishing 18 points clear of the bottom three.
Said Gallagher: “The boys did unbelievably well on the pitch, we can only give them certain instructions but then it is up to them.
“The attitude was that we set out to win every game we played, no matter who we were playing.
“It was 11 versus 11, whoever did the better job on the day would win it.
“No one has a right to win, it has to be earned. It is two teams playing, names on a piece of paper
“The players listened to us, worked hard, played with a smile on their faces and you saw what the end result was.
“We learned a lesson from one defeat and were unbeaten after that.”