Bryant, a retired NBA basketball star who played for the Los Angeles Lakers, his 13-year-old daughter Gianna and seven others died in a helicopter crash in January. Kimmel gave the opening speech at Bryant and Gianna's memorial service in February, which was televised.
When asked how intense and nerve-wracking the experience was, Kimmel said "very and very."
"I guess I wasn't fully paying attention, but I didn't know it was going to be a televised event," he said. "I thought it was a somewhat intimate family and fans thing."
Kimmel said it was heartbreaking to see Bryant's wife, Vanessa Bryant, and surviving daughters Natalia, 17, Bianka, 3, and Capri, 10 months, at the ceremony.
"The saddest part was seeing the family just sitting in the front row, that really, that's a killer -- to look out at those kids and Vanessa and Kobe's parents and to just realize as sad as this is for all of us, this is a million times worse for them," he said.
Kimmel had shared a message of gratitude in his speech at the celebration of life service at the Staples Center in Los Angeles.
"This is a sad day. But it is also a celebration of life of ... their lives. And of life itself in the building where those of us who are Lakers fans and Kobe fans celebrated so many of the best times of our lives," the late-night talk show host said.
"I've been trying to come up with something positive to take away from this and it was hard because there isn't much. But the best thing I think I was able to come up with is this: gratitude. It seems to me that all we can do is be grateful for the time we had with them. And for the time we have left with each other. And that's all," he added.
On WWHL, Kimmel also shot down the possibility of him doing a cooking show. Kimmel has been sharing cooking videos amid the coronavirus pandemic.