The Dungannon man, who made 60 appearances for his home Province over eight seasons is one of seven players departing this summer.
Ian Nagle - who joined on loan from Leinster - Jack Owens and Portadown College duo David Busby, Caleb Montgomery (who is joining Worcester Warriors, will also leave along with, of course, Darren Cave and Rory Best who are both retiring.
Nelson was one of the most reliable backs on the periphery of the squad and could play in most positions.
He told Ulster Rugby: “I’m very proud to have played as many times as I have. Like a lot of us who were born here, it’s been a dream of mine to have played for Ulster, and to have done it for as long as I have is massive.
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“I’m very proud of that and my family are very proud of that. It’s been a dream come true.”
Reflecting on his time in the set-up, he added, “Whenever you get your first cap, you’re absolutely delighted, then you just want to play more and more. I’m really pleased to get 60 caps, starting out I never thought that I would get to that.
“My first cap was obviously special, making my debut against Leinster.
“And my first game back from injury after 14 months out was also massive for me,” he said, in reference to his return from a foot injury in the game against Edinburgh in February 2017.
“It look a long time and a lot of hard work and I’ve just enjoyed recently getting the opportunity to play.
“I’ve played in some brilliant matches and played with some unbelievable players over the years, so I have very fond memories.”
The 26-year-old admits that he will miss being part of the squad next season.
“I’ll be sad to leave. It’s my home Province and I’ve some amazing friends here, who I’ll definitely keep in contact with,” said Nelson.
“The other thing is, and I think I’ve spoken about it before… a Friday night at a packed Kingspan Stadium in pretty incredible and it’s a credit to the supporters who turn up week in, week out.
“There’s no better feeling than running out at home in front of a packed house. The roar of the crowd will be missed, definitely.”
While he won’t be involved in the next campaign, the versatile back has predicted a positive future for Ulster after a resurgent 2018/19 season with Dan McFarland at the helm.
“I think the squad has taken massive leaps forward. Going out at the quarter-final stage in Europe and the semi-final of the PRO14, it was obviously disappointing for those journeys to end the way that they did, but this squad has definitely taken big steps in the right direction over the last year or 18 months.
“I can guarantee that they will compete for silverware in the near future because I see the effort and commitment all the boys show day in, day out and how hard the coaches and support staff work as well.”
As well as the players, three of the backroom staff are leaving, scrum coach Aaron Dundon, GPS analyst Chris Hagan and Kevin McGeary, strength and conditioning coach
Head Coach Dan McFarland said: “A lot has been said about Rory and Darren in recent weeks, and rightly so – they have both been magnificent servants to Ulster Rugby and will leave a lasting legacy.
“Pete is a player who can be very proud of what he has contributed during his career at Ulster Rugby, which spans eight years including his time in the Academy.
“His work ethic and resilience, particularly when coming back from some difficult injuries, are a great example to others, and he displayed no shortage of skill as well.
“We will also say goodbye to David, Jack and Caleb who have come through the pathway here in Ulster, and also Ian Nagle, who made a positive contribution since joining us on loan in November.
“Aaron is moving on, but the work that he’s done, particularly in developing our young front row players, has been really good.”
“We’ve taken considerable steps forward in that area. Kevin and Chris have also played integral roles within the set-up for a number of years and leave us in a better place due to their involvement.”