Robert, an attorney, died aged 59 on 30 September 2003, two months after being diagnosed with oesophageal cancer.
He gained public recognition after helping defend sports star OJ Simpson, who was on trial for the murder of his ex-wife Nicole Brown Simpson and her friend Ron Goldman.
On Saturday (30 September), the media personality sisters both marked 20 years since Robert’s passing with posts on their Instagram stories.
Kourtney, 44, is the eldest of Robert’s four children with his ex-wife, Kris Jenner.
She shared a photo of Robert smiling widely and waving at the camera, and added the caption: “I miss you Daddy, 20 years ago today since I haven’t seen you.” She concluded her message with a dove emoji.
Khloe, 39, Robert and Kris’s third child, shared a text post with her followers featuring white hearts and shooting stars emojis.
“The orbs are my daddy,” she wrote. “I miss you.”
Kim and Rob Kardashian are the second and fourth children of the original Kardashian family unit.
Kris and Robert divorced in 1991, before she went on to have daughters Kendall and Kylie with Caitlyn Jenner.
Robert’s children have repeatedly shared memories of him throughout their years in the public eye, on their reality TV programmes as well as on social media and in interviews.
In 2020, Kim shared a video of herself crying after watching a hologram of her father delivering her a message for her 40th birthday.
Earlier this year, she shared a post for Robert on what would have been his 79th birthday.
“It’s almost getting to the point where I’ve had to remember you longer than I’ve known you,” she wrote in February, captioning a post that included several photos and videos of Robert and his children.
“It’s been 20 years since we’ve celebrated your birthday here on earth. But I will take it because I had the best dad in the whole wide world and am so lucky I had 22 years with you!”
Kim added her wish for her father to have been able to meet his grandchildren, including her four children with ex-husband Kanye West: North, 10, Saint, seven, Chicago, five and four-year-old Psalm.
“God you would love them so much!” she wrote.
Rob, who largely lives a life outside of the public eye, also shared a post for his father’s birthday earlier this year: a photo of the Kardashian patriarch and his young children.