A notable figure during the Swedish Deluge, Opaliński was a skilled diplomat who opposed King John II Casimir and published many of his works concerning the daily political or social matters in the Polish–Lithuanian Commonwealth.

Opaliński opposed most of Władysław's military proposals (from increasing the army to the war against the Ottoman Empire), although he supported his idea of sea tariffs.

In 1645 he led a diplomatic mission to Paris, where he was a proxy of king Władysław IV during his marriage to Marie Louise Gonzaga, whom he escorted back to Poland afterwards.

In 1647 Opaliński purchased the town of Sieraków from his brother Łukasz and, in 1650, opened the first modern school in Poland, using the didactic materials prepared by Jan Amos Komenski (Komenský, Comenius).

Many other voivodes of other voivodeships followed their suit, especially Prince Janusz Radziwiłł in the Grand Duchy of Lithuania (although Krzysztof's brother, Łukasz Opaliński, remained loyal to the Polish king).

He was the author of numerous works, including Satyry, albo Przestrogi do naprawy rządu i obyczajów w Polszcze należące (Satires, or Warnings Related to the Reform of Government and Customs in Poland) published in 1650, in the aftermath of the Khmelnytsky Uprising that spelled the end of the Golden Age of the Commonwealth.

... Zamykam, jakom zaczął, że Bóg Polskę karze Najwięcej za poddanych, ba, i karać będzie, Jeżeli się, Polaku, nie obaczysz kiedy.