In a statement posted on Instagram on Saturday, Ms Gibbins said her brother’s ability to make her laugh is what she “loved most” about him, adding she was “in awe” of his talent.
It comes as their father is in Buenos Aires to arrange the repatriation of the One Direction singer’s body.
Geoff Payne read letters and cards from fans on Friday outside the Casa Sur Hotel in the Argentine capital, where the British star, 31, fell from a third-floor balcony on Wednesday.
Liam Payne’s father arrives in Argentina after singer’s death
The singer’s family said they were “heartbroken” by Payne’s death, adding: “Liam will forever live in our hearts and we’ll remember him for his kind, funny and brave soul.”
Ms Gibbins wrote: “My brain is struggling to catch up with what’s happening and I don’t understand where you’ve gone.
“What I love most about you is your ability to make me laugh, I never chuckle as much as I do when I’m with you with anyone else.
“I’m always in awe of your talent, it should be illegal to be so talented and just have the ability to not only be good at things but be bloody great at everything you attempt, without even knowing you’re absolutely smashing it each time.”
Ruth also wrote: “I don’t feel this world was good enough or kind enough to you, and quite often over the last few years, you’ve had to really try hard to overcome all that was being aimed at you.
“You just wanted to be loved and to make people happy with your music. You never believed you were good enough, I hope you can now see this outpouring of love that you never received in your time.
“Thank you for changing my life, thank you for the incredible memories, thank you for being the best brother and friend I’ll ever have.”
Ruth also wrote: “I’m sorry I couldn’t save you” and added: “One last time I need you to know, I’m here if you need anything, I’d drive to the end of the universe to bring you back.”
She also said that her family would “take care of Bear”, Payne and Cheryl’s seven-year-old son.
“Liam knew he could call me anytime, any day and I would pick up or that I would always fetch him if he needed to just come home,” Ruth said.
His former partner, Girls Aloud singer Cheryl, said she was concerned about protecting their seven-year-old son, Bear, after the death of his father, whom she was with from 2016 to 2018.
“As I try to navigate this earth shattering event, and work through my own grief at this indescribably painful time, I’d like to kindly remind everyone that we have lost a human being,” she wrote in a post on Instagram.
Sharing a black and white picture of Payne in bed with Bear as a baby, she added: “Liam was not only a pop star and celebrity, he was a son, a brother, an uncle, a dear friend and a father to our 7 year old son.
“A son that now has to face the reality of never seeing his father again.”
The 41-year-old concluded the statement urging people to give Payne “the little dignity he has left in the wake of his death to rest in some peace at last”.
Liam Payne and girlfriend Kate Cassidy (Ian West/PA)
Payne’s girlfriend Kate Cassidy said she was at a “complete loss”, in a post to her Instagram story, adding: “Nothing about the past few days have felt real.
“Liam, my angel, you are everything. I want you to know I loved you unconditionally and completely. I will continue to love you for the rest of my life. I love you Liam.”
Meanwhile, music mogul Simon Cowell said he was “truly devastated”, adding that he felt “heartbroken” and “empty”.
Payne found fame alongside Niall Horan, Louis Tomlinson, Zayn Malik and Harry Styles when The X Factor creator Cowell put them together to form One Direction on the ITV talent show in 2010.
“Every tear I have shed is a memory of you,” he wrote in a statement on Instagram.
The 65-year-old said Payne’s son “will be so proud of everything you achieved, and how you achieved it”.
Payne first auditioned for The X Factor in 2008 when he was 14, singing Frank Sinatra’s Fly Me To The Moon, with judge Cowell telling him to return to the talent show two years later.
In 2010 he impressed the judges with a rendition of Michael Buble’s Cry Me A River before being put with four other solo hopefuls at the boot camp stage of the competition – the group which later became One Direction.
“I had to tell you when you were 14 that this wasn’t your time. And we both made a promise that we would meet again. A lot of people would have given up. You didn’t,” Cowell said.
He also said that Payne had visited him last year where they “reminisced about all of the fun times we had together”.
“After you left, I was reminded that you were still the sweet, kind boy I had met all of those years ago,” he added.
Horan was the last bandmate to share a touching tribute, saying he will “cherish every moment” he had with Payne “forever”.
Payne was spotted dancing at Horan’s show around two weeks ago at the Movistar Arena in Argentina alongside his girlfriend.
“I feel so fortunate that I got to see him recently. I sadly didn’t know that after saying goodbye and hugging him that evening, I would be saying goodbye forever. It’s heartbreaking,” Horan wrote.
Payne’s other bandmembers also paid separate emotional tributes on social media, while a joint statement from the group said they were “completely devastated” and will miss the singer “terribly”, adding the “memories we shared with him will be treasured forever”.
Payne died of multiple traumas and “internal and external haemorrhage”, a post-mortem examination report said.
Argentina’s National Criminal and Correctional Prosecutor’s Office No 16 said it was investigating the incident as an “inconclusive death”.
