Antonsson is set to join Leeds for a fee rising to almost £2million after completing a medical and finalising personal terms.
The 25-year-old - the leading scorer in Sweden’s top division this season - travelled to England over the weekend after United struck a deal with Kalmar.
Antonsson, who previously worked with new United assistant Pep Clotet at Halmstads, caught the eye of English clubs with a tally of 10 goals in 12 games for Kalmar.
Aston Villa were also linked with him but an offer made by Leeds last week cleared the way for Antonsson to hold talks with United.
The forward is set to become Leeds’ first arrival of the close season and the first since the club named Garry Monk as head coach three weeks ago.