[6] His father, Stanisław Żaryn, was a prominent architect in post-war Poland,[7] while his mother Aleksandra [pl] was a lawyer and a translator.

[11] At the time, he dismissed the Workers' Defence Committee (KOR) and the Independent Students' Association (NZS) as factions in an internecine fight of the communists,[12] and opined that the only organisation that could be trusted was the Catholic Church;[13] despite that, he cooperated with the anti-Communist opposition and joined the Solidarity movement in 1989.

[14] On 10 November 1982, during martial law in Poland, Jan Żaryn was arrested for one month during a demonstration on the charge of participating in street incidents.

In 1996, he defended his doctoral thesis in the Tadeusz Manteuffel Institute of History of the Polish Academy of Sciences,[3] which he joined the following year.

[3] In 2000, Żaryn became employed in the Bureau of Public Education of the Institute of National Remembrance (IPN), which he directed from January 2006 until April 2009.

[18] Since 2012, he presided over the editorial board of Na poważnie, a historical monthly magazine,[28] which was reorganised as W Sieci Historii [pl] the following year, where he retained his position as editor-in-chief.

[6][30] In 2011, he headed an organization Polska Jest Najważniejsza, a social committee supporting Jarosław Kaczyński in the presidential election.

[40][41] He added that "even if some of the Polish locals participated in this 'spectacle' under duress... the majority looked in disgust at what the Germans have done..."[40] Żaryn has stated that the current narrative about the Jedwabne events had become a "founding myth" about the "allegedly proven" organized massacres of Jews by Poles, supposedly rooted in inherent Polish anti-Semitism.

[43][42] Żaryn is a vocal critic of Jan Tomasz Gross, and has condemned various books of his, indicating that they "are part of a certain kind of Jewish (mainly testimonial, but also scholarly) literature and historiography that is soaked with deep resentment towards Poland and the Poles".

For instance, Żaryn argued that the Polish Round Table Agreement had been a sort of a conspiracy and that the government of Jan Olszewski had been overthrown in a coup d'état.

[12][13][49] In 2009, in connection with the radio criticism on awarding the victim status of a person repressed by the communist government to Lech Wałęsa, Żaryn was dismissed from the Public Education Office of the Institute of National Remembrance.

[55] In 2009, President Lech Kaczyński bestowed upon Żaryn the Commander's Cross of the Order of Polonia Restituta, for his "extraordinary achievements in documenting and commemorating the truth about the contemporary history of Poland".