Jo’s senseless killing gave Kim and her loved ones a profound and painful insight into the agony inflicted on other families last year as terrorists mounted four deadly attacks on British soil in the space of 89 days.
The outrages at Westminster Bridge, Manchester Arena, Borough Market and Finsbury Park sought to sow seeds of division, not just in the communities targeted by the killers but in towns and cities across the land.
And today, one year on from the first horrific incident, the attack at Westminster Bridge that claimed five innocent lives, Kim has spoken of her pride at the way the country pulled together during those days of fear and confusion.
Echoing her sister’s famous message that we have “more in common”, she told the Yorkshire Evening Post: “I think what my family has been a part of and what we’ve observed is how, when the worst of human behaviour is on display, it actually often brings out the best of humanity.
“I think that happened to us as a family and a community when Jo was murdered.
“I think we also saw examples of it after Westminster Bridge, Manchester Arena, Borough Market and Finsbury Park.
“I guess what is quite sad, though, is that it takes such tragedy to bring out the best in people and a lot of the work that I have been trying to do is to get people to pull together in that way all the time.”
Like mum-of-two Jo, the 36 victims of last year’s wave of terror attacks each left behind an enduring legacy of love.
But they also left behind mothers and fathers, brothers and sisters and husbands, wives and children with hearts broken and dreams cruelly shattered.
“Mum and Dad and I have spoken about this and whenever such horrendous events occur, that is the first thing you think about because you know from that moment their lives will never be the same again,” said Kim.
“You feel empathy with families that have lost loved ones. I don’t think you can fully understand the depth of emotion it creates unless you have been through something like that.
“I met some parents who lost a daughter in the Manchester attack and they were lovely.
“It really was like meeting kindred spirits and we did understand some part of what each other had been through.
“I think it’s important that we show that, even though we are at the acute end of such tragedy, we won’t lose our faith in people.”
That determination to ensure good can come from evil has been a driving force of events such as last year’s Great Get Together, when millions of people nationwide took part in community celebrations large and small over the course of one memorable weekend in June.
It is being held again this year on June 22 to 24, coinciding with what would have been Jo’s 44th birthday.
Kim is also set to take on a more prominent role with The Jo Cox Foundation following the resignation of her sister’s widower, Brendan Cox, amid claims about his private life.
And she wants to use her profile and platform to try to stop anyone else making the same twisted choices as Khalid Masood, the 52-year-old who drove at and stabbed his victims on Westminster Bridge, Bridge Street and in the grounds of Westminster itself on March 22 last year.
“We need to ensure we have communities where everyone feels a sense of belonging and everyone feels they have a valuable part to play,” said Kim.
“If we have disengaged and disenfranchised people then we are dealing with, on one level, issues of loneliness and social isolation, but we are also potentially dealing with much more serious and darker issues in terms of people being drawn towards extremism of any nature.”