The singer, from Cardiff and now based in Los Angeles, reached number one with his track Babydoll.
In doing so, he became the first Welsh artist to claim the top spot since 2011, when Sian Evans featured on DJ Fresh’s hit Louder.
He is also the first solo male Welsh artist to achieve a UK number one in 41 years, following Shakin’ Stevens’ 1985 festive classic Merry Christmas Everyone.
Speaking to the Official Charts, Miller said: “I don’t even know what to say other than thank you so much for getting me number one.
“This is the biggest thing that’s ever happened to me in my life, I love you guys.”
Babydoll was released in August and entered the charts in September at number 84.
It grew in popularity after actress Jennifer Love Hewitt posted videos featuring the track – even joking she was dealing with “Babydoll-itis” as she couldn’t stop listening to the song.
Since then it has steadily climbed to number two last week before reaching the top spot.
The chart battle was close, with just 556 chart units separating Mr Miller from this week’s number two, Tate McRae’s Housewife.
The song has sparked a TikTok dance trend, and celebrities including Little Mix’s Perrie Edwards, Stranger Things actor Noah Schnapp and This Morning host Alison Hammond have joined Miller dancing to Babydoll.
The singer first rose to prominence as a finalist on The Voice UK in 2017, where he finished in third place.
He was born in Cardiff to Scottish parents and grew up in Pontprennau.
And last month, Miller performed in his first arena venue as he opened for the Jonas Brothers during their The Burning Up Tour.
