The 24-year-old Sweden international has arrived at Turf Moor on a four-and-a-half-year deal.
The centre-back started his career in Sweden with Brommapojkarna FC before moving to the United States at the age of 18.
Ekdal studied and played collage soccer for UNC Wilmington Seahawks, though his journey in America was over a year later.
The 6ft 2in Swede returned to his home country and linked up with IK Frej where he made 15 appearances.
In the summer of 2019, Ekdal joined top-tier side Hammarby IF.
The 24-year-old enjoyed a loan spell at IK Sirius before permanently moving to Djurgardens in January 2021.
Ekdal said: "Burnley and Vincent Kompany have done amazing things so far this season, it's something I really wanted to be a part of.
"It feels really good, I can't wait to meet the team now and play in front of the amazing crowd at Turf Moor."
The player has become Vincent Kompany's second signing of the January transfer window.