Guðni spent part of the 1988-1989 season with University of Wisconsin–Oshkosh but left the school in late January 1989 and returned to KR in Iceland.

[3] In 1986 he was named the Icelandic Basketball Player of the Year and in 1988 to the Úrvalsdeild Domestic All-First Team.

During his second season KFÍ achieved a fifth-place finish with a 13-9 record but lost in the first round of the playoffs to eventual champions Njarðvík, 2-3.

[8] Guðni stepped down as coach and semi-retired as player after that season, only playing a handful of games when injuries plagued the main squad.

[10] Guðni coached Division I club ÍS from 1994-1996 and led them to 27-9 record and two playoffs berths.