Theresa May made a vow to the children of murdered MP Jo Cox to wipe out loneliness in her memory.
At a Downing Street reception to celebrate the Labour politician's legacy, the Prime Minister said the ideals the campaigner stood for would not be forgotten.
Tracey Crouch has been made minister for loneliness following a series of recommendations made by the Jo Cox Commission set up to tackle the issue.
Mrs Cox, who was brutally murdered by a far-right terrorist, campaigned across the political divide before her death to find ways to combat loneliness.
Widower Brendan Cox has previously described how son Cuillin, aged just five when his mother was killed, wrote a song in tribute to her that went: "I love my mummy, I will not leave her behind."
At a reception in No 10 attended by Mrs Cox's family, the PM said: "Cuillin, don't worry. None of us will leave your mummy behind.
"None of us will forget her life, her ideals or what she stood for and all of us will do all that we can to see that in her memory we bring an end to the acceptance of loneliness in our society."
Parties in honour of Mrs Cox will be held across the country on what would have been her 44th birthday.
The Great Get Together, which was held last year on the anniversary of Ms Cox's death, will be held from June 22.
Mrs Cox's parents, Jean and Gordon Leadbeater, were among the guests and told of their pride in the work she did to bring people together.
Mrs Leadbeater said last year's gathering was "ever so difficult for us" but moving the date to mark her birthday was " more apt".
"From the minute Jo was murdered we decided we would celebrate her life, so I think it is a wonderful thing and it certainly helped us as a family last year to get through the year."
Mr Cox said: "Jo went into politics because she had this huge empathy with people and one of the things that worried her most was loneliness and the sense that you live in communities but those communities are less close than they used to be.
"I think today, with the appointment of the minister and with the agreement that there will be a strategy to tackle loneliness, those two key things are the beginning, they are certainly not the end, of a blueprint for how we can tackle loneliness and what has become a social epidemic in our country."