A Polish social media influencer has raised more than £50m after a nine-day, nonstop online stream during which he was joined by a parade of celebrity guests to help a charity supporting children battling cancer.

Streaming from a studio flat in right-bank Warsaw, social media influencer Piotr Garkowski, 23, nicknamed Łatwogang, listened to a charity song dedicated to children battling cancer on loop for nine days straight, filling time with entertaining dares and celebrity appearances.

The song “I’m still here”, recorded by Polish rapper Bedoes 2115 with Maja Mecan, 11, is written in the form of a rap diss track intended to insult or disrespect a rival – but aimed at cancer.

“If you suffer from cancer just like me, this song is for you. I’m Maja and this is my third relapse, and I have reasons to diss you,” the girl says.

The song – at times a battle cry, at others a deeply moving tribute to young patients, their parents, nurses and doctors – features a chorus sang by Maja: “I’m still here/Did you think you had me?/I’m still here/We laugh in your face/I’m still here/And I’m not going anywhere.”

The streamer, previously best known for recording with Ed Sheeran a Polish language version of his hit Azizam, was joined by a parade of country’s leading music artists, actors, sportspeople and influencers, who recreated their biggest viral hits and pop culture moments.

Coldplay’s Chris Martin made a brief appearance, sending a video of himself performing an improvised keyboard song featuring the Polish word for “pushing” the fundraising total even further, adding: “Sorry for my Polish!”

Joining the stream at just past 3am, Russian-born Polish-naturalised speed skater Vladimir Semirunniy donated his silver medal from the Milan-Cortina Winter Olympics in the 10,000 metres event, before following the host’s example and shaving his head in solidarity, as did numerous other guests.

The campaign also received high-profile endorsements on social media, with Poland and Barcelona’s footballer Robert Lewandowski dancing to the song on his TikTok and donating more than £200,000.

A teammate, ex-Arsenal goalkeeper Wojciech Szczęsny, also recorded a social video in which he was joined by Barcelona and Spain’s Lamine Yamal.

Six-time tennis grand slam champion Iga Świątek also gave her support, donating more than £20,000 and two tickets to her match at this year’s Wimbledon tournament.

Despite an initial goal of just 500,000 złoty (£102,000), the stream is understood to be among the highest-ever fundraising events on YouTube. As of Monday morning, the total raised during the stream topped 257m złoty (£52.5m), with more than 1.5 million people watching the finale with Łatwogang, Bedoes 2115 and child cancer patients live on Sunday night.

On Monday, Łatwogang and Bedoes 2115 thankedsupporters on Instagram, congratulating them for “what you did for the kids and [how you] moved the entire country”.

“We ask the media … to publicise the fundraiser and the awareness that cancer is not a death sentence. Because that is all we care about,” they added.

The money will support the Cancer Fighters foundation that supports children with cancer and their parents, with a public promise that every penny will be publicly accounted for on a special website.