Paying tribute on her ITV chat show, Kelly said it had been "beautiful send off" that was a celebration of "an amazing, amazing woman".
And she shared that some of those at the service had agreed to get a tattoo of Dame Deborah's well-known phrase "Rebellious Hope".
She said: "I think yesterday there was a whole bunch of us who said we are going to get tattoos with 'Rebellious Hope' on them.
"I think I agreed to it."
Kelly said Dame Deborah was the only person she would do that for.
Kelly also said that as well as all of her fundraising and work to raise awareness, Dame Deborah's son Hugo, 14, and daughter Eloise, 12, were her legacy.
"We talk about her legacy and her legacy is astonishing, what she's done to raise awareness," she said.
"But her legacy is also her children and they are, wow, they are incredible, incredible young people. They really are."
Dame Deborah was diagnosed with bowel cancer in 2016.
In May this year she penned a moving message on Instagram, saying that she had moved to hospice care as her body was no longer "playing ball".
And in the last weeks of her life, Dame Deborah helped to raise more than seven million.
She passed away peacefully on 28 June, surrounded by her loved ones.
Watch: Friends and family bid farewell to Deborah James at intimate service