The following year he enrolled in the seminary in Włocławek, and on his 23rd birthday (3 August 1924), after being hospitalised with a serious illness, he received his priestly ordination from Bishop Wojciech Stanisław Owczarek.

[4] Wyszyński celebrated his first Solemn High Mass of Thanksgiving, at Jasna Góra in Częstochowa, a place of special spiritual significance for many Catholic Poles.

When the Second World War broke out with the German invasion of Poland in 1939, he was forced to leave Włocławek because he was wanted by the Gestapo: he had written articles critical of the Nazis in a Catholic journal.

When the Warsaw Uprising broke out on 1 August 1944, he adopted the nom de guerre "Radwan II" and became chaplain of the insurgents' hospital in Laski, and of the Żoliborz military district of the Armia Krajowa, the Polish underground resistance organisation.

While there, he and another man helped hide a widowed Jewish labourer and his two children – who would be denounced by a Ukrainian nationalist and killed by the Germans in October/November 1942, five months after the liquidation of the local ghetto in Kraśniczyn[8] – in an attic.

Additionally, Esther Grinberg, in her testimony held at the Yad Vashem Institute in Jerusalem, credits the Polish assistance that saved her life to Wyszyński's veiled injunction, possibly in a sermon, to rescue "those running from the fire".

[9][10] In 1945, a year after the end of war in the area, Wyszyński returned to Włocławek, where he started a restoration project for the devastated seminary, becoming its rector as well as the chief editor of a Catholic weekly.

He also claimed that Jewish books consulted during trial of Beilis had not dispelled the accusations of ritual murder, and demanded that the Jews leave Poland.

World War II ended in 1945; however, beginning in the eastern portion of present-day Poland, and later in the west, hostilities continued for several years between a large segment of Poles and the Stalinist government.

The Catholic Church hoped for the return of the Polish government-in-exile from London and the removal of Stalin's puppet regime; it actively supported the anti-Communists.

[13] On 25 September 1953 he was imprisoned at Rywałd, and later placed under house arrest in Stoczek Klasztorny [pl] near Lidzbark Warmiński, in Prudnik near Opole and in the Komańcza monastery in the Bieszczady Mountains.

On 12 January 1953, Wyszyński was elevated to the rank of cardinal by Pope Pius XII,[14] but it was not until 18 May 1957 that he was designated Cardinal-Priest of Santa Maria in Trastevere.

Wyszyński triumphed in 1978, when Karol Wojtyła of Kraków was elected Pope John Paul II, followed by a spectacular papal visit to Poland in 1979.

Wyszyński's major achievement was to preserve the position of the Catholic Church as a powerful social institution in Poland into the Communist era.

[20] Theologians met to discuss the contents of the Positio on 26 April 2016 and voted in favor of the late cardinal's life of heroic virtue.

An investigation on a diocesan level was initiated on 27 March 2012 for an alleged miracle attributed to him which concluded its business on 28 May 2013; the process was validated on 10 October 2014.

[21][22] The medical experts in Rome approved the miracle on 29 November 2018 with theologians later confirming it as well as the cardinals and bishops comprising the Congregation on 24 September 2019.