|Date of birth||25 June 1994|
|Place of birth||Bergen, Norway|
|Height||1.93 m (6 ft 4 in)|
|2013||→ Vard Haugesund (loan)||3||(0)|
|2015||→ Nest-Sotra (loan)||26||(0)|
|* Senior club appearances and goals counted for the domestic league only and correct as of 5 January 2017.
Øvretveit started his youth career at his local side Telavåg, later playing for a cooperation team of Skogsvåg and Hald. Ahead of the 2009 season, he made his big move to Brann's youth system. Øvretveit signed a professional contract with Brann on 9 February 2011, which allowed him to play in league and cup matches for the first team. A successful year with the youth team culminated in an appearance in the Norwegian under-19 Championship.
On 18 November 2011, Øvretveit was taken out of training for an indefinite period after doctors found an irregular heartbeat in routine cardiac checks. Despite being unsure of whether he had a future in football at all, he was cleared to train again by his doctors on 19 January 2012 when it was found that his problem was only temporary.
Øvretveit's ambition ahead of the 2012 season was to establish himself as Brann 2's first-choice goalkeeper. But with the regular substitute goalkeeper Jørgen Mohus out injured, Øvretveit started the 2012 season on the bench. In the season opener against Rosenborg, injury forced Piotr Leciejewski to come off as a first-half substitute, allowing Øvretveit to come on for his professional debut. He became Brann's youngest goalkeeper in the Premier League, taking the record from his current goalkeeper-coach Dan Riisnes.
On 16 May, Leciejewski was again injured and Øvretveit replaced him in Brann's 5–0 victory against Sogndal. In the next match, he started his first league match, away against Aalesund. Although he conceding two goals, his performance was praised by Aalesund's coach Kjetil Rekdal, who stated that it wasn't Øvretveit's fault that Brann lost.
Øvretveit joined Nest-Sotra on loan.
- As of 26 April 2015
- "Alle Eliteserie-overgangene i januar" (in Swedish). m.nettavisen.no. Retrieved 4 January 2017.
- Støverud, Erik Bentdal (5 November 2009). "Keeper fra Telavåg fikk Brann-stipend". VestNytt (in Norwegian). p. 28.
- "Øvretveit får proffkontrakt" (in Norwegian). SK Brann. Retrieved 20 May 2012.
- "Stegavik avgjorde for Rosenborg" (in Norwegian). NFF. Retrieved 20 May 2012.
- "Øvretveit tas ut av trening" (in Norwegian). SK Brann. Retrieved 20 May 2012.
- "Øvretveit er frisk igjen!" (in Norwegian). SK Brann. Retrieved 20 May 2012.
- "- Utrolig gøy å få sjansen" (in Norwegian). NFF. Retrieved 25 May 2012.
- "Øystein Øvretveit" (in Norwegian). SK Brann. Retrieved 13 May 2012.
- Juva, Geir (27 March 2012). "Børs-kommentar". VG Sport (in Norwegian). p. 6.
- Ellingsen, Roy (21 May 2012). "En mann på 17 år". Bergens Tidende (in Norwegian). Retrieved 21 May 2012.
- "Skikkelig Piotr-smell". ANB-NTB (in Norwegian). ba.no. 16 May 2012. Retrieved 21 May 2012.
- "Brann-keeper til Vard" (in Norwegian). TV 2. Norwegian News Agency. 14 June 2013. Retrieved 7 August 2013.
- "Øystein Øvretveit". altomfotball.no (in Norwegian). TV 2. Retrieved 7 August 2013.
- Øystein Øvretveit at Soccerway