The Cork-born presenter played a leading role in the success of the show since it started in 1999 and today he took his final bow.
Surrounded by the show’s cast and crew, Cagney made an emotional speech thanking everyone he has worked with during his time at the show.
As a special gesture, he was then gifted one of Bono’s guitars followed by a montage of Mark's best moments over the past twenty years.
Fellow presenter Ciara Doherty made a surprise return from maternity to wish him well, along with current presenters Karen Koster, Alan Hughes, who were both visibly emotional throughout the show.
Messages from fans were read out to mark the occasion. Mark gave a special mention to a woman named Sue, who made him a card featuring photos from the past 20 years.
Chef Catherine Leyden baked his favourite dish - bread and butter pudding - whilst resident gardener Paraic Horkan gifted Mark with a plant.
And it didn’t end there, fans and colleagues have been flooding social media with best wishes for Cagney.
Others commented on how emotional and poignant today’s show was.
This absolute gent is presenting his final @IrelandAMVMTV this morning.
I like so many have nothing but respect and admiration for him. He’s genuinely “one of the good guys”. I feel lucky to have spent some studio time with a total pro 🙌🏼 #IrelandAM #MarkCagney pic.twitter.com/LZ0XfQK71I— Suzanne Kane (@SuzanneKaneFM) July 31, 2019
OK I am bawling now.
So much genuine love and respect for Mark Cagney from all the team and viewers of @IrelandAMVMTV
Regardless of your hugely successful 20 year career on Breakfast telly...you are clearly a gorgeous human.
Stand tall Mark.
Beautiful sign off.— Síle Seoige (@SileSeoige) July 31, 2019
Crying over Mark Cagney leaving Ireland AM right now, what a start to the day 😭— kelsey (@kelseykirby_x) July 31, 2019
What an emotional goodbye to #markcagney on #irelandam. That programme has been a major part of life for the last 20 years...my distraction in the chemo waiting room been the main part ... tried to help me forget what I was about to go through..legend at his job— Cory Ni Mhuineachain (@CoryMonaghan) July 31, 2019
Happy trails to Mark Cagney - presenting his final @IrelandAMVMTV today.
An absolute gent, a very sharp interviewer and a terrifically kind person whenever I've worked with him.
Presenters leaving shows goes over my shoulder but Mark leaving #IrelandAm is like an end of a era. Marks voice has been on in the background every morning during major events and normal days too....First day of school, Leaving Cert, LC results day first day of college etc 1/2— Niamh Sheahan (@_Niamhs) July 30, 2019
Seeing my Mam so emotional watching @IrelandAMVMTV and Mark Cagney leaving is pretty outstanding. He has been a part of our home every morning as background noise for as long as I can remember. I’ll miss his kind and caring voice and no doubt Mam will miss him more💚Le Grá☀️— Niamh Ní hAoileáin (@niamhylo) July 31, 2019