'I won't ever be prepared': Kathy Griffin's tribute to her mum, Maggie

US comedian Kathy Griffin has shared a tender tribute to her mother, who died on Tuesday, March 17.

"My Mom, the one and only, Maggie Griffin, passed away today. Hours ago. I am gutted." Griffin wrote on Instagram.

"She was my best friend. She was my family. You knew her," she went on. "I'm shaking. I won't ever be prepared."

Griffin explained that Maggie was perhaps the only person who ever truly "got" her, and didn't shy away from talking about how devastating it was to lose her.

"I'm telling you right now, I am not doing well with this," she wrote – then finished on a bittersweet note.

"Oh, and OF COURSE she went on St Patrick's Day."

Griffin posted a photo of the two of them sitting arm-in-arm, gazing out over a very glamorous pool and drinking white wine.

Maggie, 99, provided material for a lot of Griffin's stand-up, regularly starred alongside her in her reality show, Kathy Griffin: My Life on the D-List – and as Griffin pointed out, had a fervent fan-base of her own thanks to her wry and witty sense of humour.

"Oh Kathy! I am so sorry," actor Selma Blair wrote in a comment on the post.

"She was always making me laugh when I watched you two. This grief will be deep. And hard. I am sure. Feel it. It will lessen. And she will be in every bottle of white you open. And everywhere else you find her spirit... sending strength. And massive hugs."

"Oh Kathy. I am so, so sorry. We love you," Chrissy Teigen added on Twitter

In January last year, Griffin revealed to fans on Twitter that Maggie was fighting dementia.

"This is never easy for any child, I know this is a reality that millions of people deal with every year," Griffin wrote. "But when it comes to my mom this is particularly hard because her sharp mind was everything."

Maggie's death is not the first tragedy the 59-year-old has had to contend with recently: three years ago, she lost her older sister, Joyce, to cancer.

READ MORE: Kathy Griffin's sister Joyce loses her battle with cancer at age 65