Benedikt Jóhannesson is born in Reykjavik on the 4th of May 1955, the son of Jóhannes Zoëga (born 14 August 1917, died 21 September 2004), the manager of the Reykjavík Geothermal Heating System, and Guðrún Benediktsdóttir (born 10 October 1919, died 11 March 1955), the deputy manager of the Althingi staff office and the daughter of Benedikt Sveinsson, a member of the Althingi.
Married to Vigdís Jónsdóttir (born 11 March 1955), the deputy manager of the Althingi staff office. Her parents are Jón I. Bjarnason and Guðbjörg Lilja Maríusdóttir.
The have three children: Steinunn (1978), Jóhannes (1980) and Jón (1988).
Benedikt graduated from the Reykjavík High School (Menntaskólinn í Reykjavík, MR) in 1975. He holds a B.Sc. degree in mathematics with a minor in economics from the University of Wisconsin in 1977, an M.Sc. degree in statistics from Florida State University in 1979 and a Ph.D. in statistics as a major subject and mathematics as a minor, also from Florida State University, in 1981.
Taught at Verslunarskóli Íslands 1982-1986. Founded the consulting firm Talnakönnun in 1984 and has managed it since. Has been the managing director of the Heimur publishing company since 2000. He has sat on the boards of several companies and been a member of numerous committees and commissions.
- Chairman of Viðreisn, the political party, since its founding in 2016.
- MP for the North-East constituency for Viðreisn since 2016.
- Chairman of the Economic and Trade Committee of the Althingi since 2016.
- Editor of the journals Ský since 2005 and Vísbending since 2006.