The 21-year-old winger, who was born and raised in Chad, joins the Clarets on a five-year deal for an undisclosed fee.
Tchaouna arrives at Turf Moor with a wealth of experience despite his young age, having already amassed 130 senior appearances across Serie A, Ligue 1, and Ligue 2.
"Itâs a very proud day for me to sign for this special club," he said, as quoted by the club's official website.
"I spoke with the manager during the Euros this summer and we had a really good conversation, which made me realise I wanted to be here.
"I canât wait to get ready for the upcoming season and to play in front of the supporters."
His journey began in the youth academies of FC Kronenbourg, Schiltigheim, Strasbourg, and Rennes, joining the latter in 2014. He made his professional debut for Rennes at the age of 17 in September 2021 against Bordeaux.
After a loan spell at Dijon during the 2022/23 season in Ligue 2, Tchaouna moved to Serie A with Salernitana for the 2023/24 campaign.
There, he impressed with six goals and four assists in 35 appearances, earning a summer 2024 transfer to Lazio. He scored his first goal for the Roman club in October against Como and featured in 37 matches across all competitions last season.
Tchaouna becomes Burnleyâs fourth summer acquisition as they look to strengthen their squad ahead of the new season. He follows goalkeeper Max WeiÃ, Dutch left-back Quilindschy Hartman, and centre-back Axel Tuanzebe through the doors at Turf Moor.