Since 2010, he is the editor of the Swedish code of laws. He received a Candidate of Law degree from Lund University in 1966. In 1974 he was employed as an associate judge (hovrättsassessor) at the Skåne and Blekinge Court of Appeal in Malmö.
The same year he was employed at the Ministry of Justice where he served as a legal adviser (sakkunnig) until 1979, assistant undersecretary (departementsråd) and head of the criminal law unit (straffrättsenheten) from 1979 to 1983, and as chief legal officer (rättschef) from 1983 to 1987.
In 1987 he was appointed as a judge of the Swedish Supreme Court. On February 1, 2007, he was appointed as chairman of the Supreme Court following the retirement of Bo Svensson.
Johan Munck has served as a commissioner of several Swedish government commissions and committees, such as the Committee on Genetical Integrity (Kommittén om genetisk integritet), the September 11 Commission (11 september-utredningen) and the Stock Market Security Paper Commission (Värdepappersmarknadsutredningen). He has served as chairman of the Swedish Stock Market Committee (Aktiemarknadsnämnden), the Disciplinary Committee of the Stockholm Stock Exchange (Stockholmsbörsens disciplinnämnd), the Swedish Broadcasting Commission (Granskningsnämnden för Radio och television) and the Swedish National Collections of Music (Statens musiksamlingar).
From 1979 to 1988 he was a judicial assistant to the Supreme Commander of the Swedish Armed Forces.
He has authored several books and articles related to criminal and civil law. He lives with his family in Sollentuna north of Stockholm. He is an outspoken Feminist.