"She was our best friend, she was a legend, she was as cool as they come. The best mum"
Marie Keating died in 1998 when her Boyzone singer son was only 20-years-old following a diagnosis of breast cancer.
Taking to social media, Ronan shared a touching video to mark the 24th anniversary of her death.
“24 years ago today I lost my mum. My family and I went through the most horrible situation losing our mum," his tribute began.
"Marie Keating, she died 24 years ago. She was 51 years of age, she died of cancer.”
Ronan and his family went on to establish the Marie Keating Foundation, a foundation focused on raising cancer awareness, and offering support to those affected.
"She was our best friend, she was a legend, she was as cool as they come. The best mum,” he continued.
Sharing his one regret about her death, the father of five said he wishes Marie got to meet his children.
“She never got to meet her grandchildren, she's got so many incredible grandchildren," he continued.
"It's heart breaking that she never got to meet them. I wonder about the conversation I'd have with my mum today, about my children, about my life.”
Ronan shares his two youngest children Cooper (4) and Coco (1) with wife Storm.
During his first marriage to his ex-wife Yvonne Connolly he fathered three children, Jack (22), Missy (20) and Ali (16).
Ronan added that he misses turning to his mother when times are rough.
"So many things in the 24 years that I've been through and I've done that I'd love to share with mum.
"When your mum puts her arms around you and says 'everything's going to be OK' - that feeling. I don't get that anymore and there's nothing like that feeling.
"When you're going through a tough time and your ma tells you 'everything's going to be alright'. Well then you think it's going to be alright. That's what happens."
His former bandmate and friend Keith Duffy shared his memories of Marie in the comments.
“Remember the Superquinn sausages and the bacon she’d give us wrapped in tinfoil for our trips to Belfast,” he said.
“And the miraculous medals and rosary beads she’d wrap around our rear view mirrors in our cars to keep us safe! Now she’d make sure we gave them back on the way home lol.
“Marie the legend, never forgotten by anyone she knew.”
TV Chef Jamie Oliver sent his best wishes too: “Big love brother xxx thank you for sharing your feelings so important...sending much love to all your gang.”
Hotelier Bill Walshe commended Ronan for using his grief to make a difference.
“Ronan, the way you and the entire Keating family channelled your grief into a force for good is simply awesome.
“One of the absolute proudest times of my life was to have been a very small part of the very big impact that The Marie Keating Foundation has had. Thank you for that opportunity. The incredible, life changing work that you guys have done in Marie’s name is such a wonderful tribute to her memory.”
Shane Lynch, Natalie Imbruglia, Brian McFadden, Angelica Ball and Pixie Lott also sent their love.