The 35-year-old made 140 appearances for Leinster after joining in 2009 and he won two PRO12 titles and a Challenge Cup, along with a Premiership title and a European Cup with Wasps.
Reddan made his Ireland debut in 2006 and could earn his 71st cap tomorrow in Port Elizabeth, while he also played for Connacht and Munster.
"His contribution over the years to the success of the team both on-field, and off-field in his role with the leadership group, has been immense and he leaves a lasting impression on all those that were lucky enough to work with him on a daily basis," Cullen said.
"In his time with us he has represented the club and his country with distinction including captaining both Leinster and Ireland.
"But what he achieved over his whole career representing four clubs and the trophies he won with Wasps, Leinster and Ireland is unique.
"He was a brilliant athlete and he achieved a huge amount at the very highest level. Hopefully he can finish on a high this weekend which would be a great way to end it all."
Follow the Guinness PRO12 on Facebook, join the conversation on Twitter, sign up to our YouTube channel for extensive match highlights and sign up for our newsletter for regular updates on the Guinness PRO12.
Guinness PRO12 Leinster News
63x46.png){kind=logo}