The singer-songwriter will compete against 39 other countries at the grand final in Turin, Italy, between 12 and 14 May.
Who is Sam Ryder?
Originally from Essex, Ryder found fame covering songs on video sharing app TikTok during lockdown.
So far, he's accumulated more than 12 million followers, making him the most followed UK music artist on the platform.
How did TikTok help his career?
His videos caught the attention of several global stars, including Justin Bieber and Alicia Keys.
He later signed to the Parlophone record label, part of Warner Music Group, and released his debut EP The Sun’s Gonna Rise in 2021. Singles from the record, Whirlwind and Tiny Riot, enjoyed great success.
He's has also recently completed his first UK tour.
Unscripted - Listen to our entertainment podcast
How was he selected for Eurovision?
Ryder was selected to compete for the UK in a collaboration between the BBC and global music management company TaP Music, which counts Lana Del Rey and Ellie Goulding among its clients.
TaP Music co-founders Ben Mawson and Ed Millett said: "The Eurovision Song Contest is truly a cultural phenomenon and an amazing opportunity – with 200 million viewers – for the right performer.
"As well as Sam having an amazing voice, Space Man is an instant song that we’re confident will really connect.
"Not to mention he’s also an extremely likeable and engaging character – as evidenced by his TikTok following."
How did he react to being chosen?
In an interview, Ryder said he was "honoured" as he's been a fan of Eurovision since he was a kid.
He added: “I hope to sing my head off in a way the UK can be proud of, and to showcase a song I wrote with my friends last summer makes the whole experience even more special.
What song will he perform?
The singer co-wrote the song Space Man with Grammy-winning songwriter Amy Wadge, who has previously worked with Ed Sheeran and Max Wolfgang.
How has the UK done in recent years?
The 2021 competition was held in Rotterdam, Netherlands, after the show was cancelled in 2020.
The UK was handed a crushing defeat as its entry, singer James Newman, was the only one to score zero points from both the jury and public vote, coming bottom on the leaderboard.
Since its first entry in 1957, the UK has had five wins - Sandie Shaw (1967), Lulu (1969), Brotherhood of Man (1976), Bucks Fizz (1981), and Katrina and the Waves (1997).
The UK holds the record for the longest run of consecutive appearances in the Grand Final of the contest - 59 times in a row.
It also holds another record for coming in second in the final ranking 15 times.
The European Broadcasting Union (EBU) said in a statement that the inclusion of a Russian entry at the contest in Turin in May would bring the contest into "disrepute".