He played professionally in Italy, Germany, France, and Spain but is best remembered for his time in Sweden with IFK Göteborg with which he was the 1986 Allsvenskan top scorer and won three Swedish Championships.
A full international between 1986 and 1995, he won 47 caps for the Sweden national team and represented his country at the 1990 FIFA World Cup and UEFA Euro 1992.
[1] He quickly earned the nicknames "Kallebäcks-Expressen" (the express train from Kallebäck) and "Johnny Bråttom" (Johnny-in-a-hurry) due to his speed on the football pitch.
[2] His most successful season with Göteborg came in 1986, when he was the 1986 Allsvenskan top scorer and helped the club reach the semi-finals of the 1985–86 European Cup before being eliminated by FC Barcelona.
[3] At Empoli, he became a popular and respected player and acquired the nickname 'Il Ciclone' (the cyclone) due to the exceptional speed he displayed when charging ahead with the ball in his possession, which was his most notable quality.
[5] Ekström spent the spring of 1994 with Real Betis on loan from Reggiana, becoming the second Swedish player to represent the Seville-based club after Torbjörn Jonsson.
[9] Ekström made his full international debut in a friendly game against Greece on 1 May 1986, playing for 71 minutes alongside Dan Corneliusson at forward before being replaced by Lasse Larsson in a 0–0 draw.
[13] He started in the third group stage game against Costa Rica, scoring the first goal in a third consecutive 1–2 loss which had Sweden eliminated from the tournament.