Career
He is currently the head coach of KFÍ along with Neil Shiran Þórisson. Playing KR
He started his career with KR and spent 11 years there, winning the Icelandic Championship in 1990, and the Icelandic Cup in 1984 and 1991. He was selected as the rookie of the year in 1983 and the All-First team in 1987-1988.
ÍSouth
In 1994 he went over to 1. division club ÍSouth as a player-coach and led them to a 16-4 record, good for first place.
The team knocked out Þór Þorlákshöfn 3-2 in the first round of the playoffs before losing 0-2 to Breiðablik in the Finals. During the 1995-1996 season he led ÍSouth to an 11-5 record and a third place finish.
ÍSouth got knocked out by eventual champions, KFÍ, 0-2 in the first round of the playoffs. KFÍ
In 1996 he took over freshly promoted KFÍ as a player-coach.
In his first season he led the team to a 9-13 record in the Icelandic Premier League, and just missed the playoffs by a tie-breaker.
He averaged 11,6 points on a 61,3% shooting. KFÍ lost in the first round of the playoffs to eventual champions UMFN, 2-3. KFÍ also made it to the Icelandic Cup final where it lost to UMFG, 71-95.
Guðni resigned as coach and semi-retired as player after that season, only playing a handful of games when injuries plagued the main squad.
He did however play for the KFÍ B-team in the 2. division, leading them regularly to regional championships and B-team national playoff. He appeared in three league games during the 2006-2007 season, with his best game coming against Valur where he scored 6 points in 7 minutes, and one game in the Icelandic Cup against Keflavík where he also netted 6 points.
Guðni scored 3494 points in 253 games with KR and KFÍ in the Icelandic Premium league, which makes him 19th on the all time scoring list. Guðni coached Division I club ÍSouth from 1994-1996 and led them to 27-9 record and two playoffs berths.
In 1996 he took over newly promoted KFÍ in the Icelandic premier league.
In his second season at the reins of the club the team posted a 13-9 record, good for fifth place in the league. In the playoffs the team lost to eventual champions UMFN 3-1 in the first round. In February 2016, Guðni returned to the sideline when he took over as head coach of KFÍ along with Neil Shiran Þórisson after Birgir Örn Birgisson resigned as coach.
