Reports first emerged that Glenn was considering a retirement a few weeks ago, and now the Broncos have confirmed the news, with the club captain to retire a one-club legend.
He has currently played 282 first grade games, and will finish on 285, should he play each of the Broncos' remaining three games against the New Zealand Warriors, Cronulla Sharks and Newcastle Knights.
All three games will be played at Suncorp Stadium, meaning he will finish his career on a ground he has called home for over a decade.
An almost permanent fixture in the Broncos' starting 13 over the years, Glenn debuted in 2009 and has since gone on to play for New Zealand and the Cook Islands.
He will retire as the club's fourth-most capped player of all time.
The 33-year-old told Broncos' players and staff of his decision this morning, according to an official club statement.
Glenn said his career was beyond anything he could have imagined.
“It was always a dream come true to play for the Broncos, but to finish my career as a one-club player here is beyond anything I could have imagined," Glenn said.
“There have been plenty of highs and lows but I have never taken for granted how special it is to be able to pull on the Broncos jersey."
“The Broncos are a family and I feel like I have grown up here and I appreciate every player, coach and staff member that has helped me along that journey.
“The Broncos have a bright future ahead, you can see that by the way we have turned things around this year, and I can’t wait to see this team grow and succeed in the years ahead.”
It's understood Glenn at one stage had entered preliminary contract discussions with the Broncos for 2022, but has ultimately decided to pull the pin on a glittering NRL career.
Versatility allowed Glenn to play on occasion in the centres throughout his career, and it goes without saying that he has always been one of the most important members of the Brisbane side.
Coach Kevin Walters said Glenn was incredibly consistent.
“Alex has played at a very high standard for a long time and led by example on and off the field.
“To be so consistent week-in, week-out since making his debut in 2009 is an incredible effort.
“He’s a true club man and will always be remembered for his pride and passion in the Broncos jersey.”