The Kiwi international will be a Bronco until at least the end of the 2019 season after inking a new deal this week.
After making his NRL debut in 2009, the 28-year-old father of two young children has now played over 200 games for the Broncos and 12 Tests for the Kiwis.
Broncos' chief executive Paul White send the retention of Glenn was something the Broncos had been working hard on.
"Alex was the captain of our first ever National Youth Competition team back in 2008, so to have him re-commit to our club is a wonderful thing for the Broncos," said Broncos' chief executive Paul White.
"We have watched Alex grow from a teenager from Auckland and the Gold Coast into a Test player and a fine young family man.
"The Broncos are very pleased he will continue to be part of our future with this new two-year deal."
Photo by: Scott Davis/ NRL Photos (Alex Glenn celebrates a try during Brisbane's big win over the Wests Tigers).