General Rajmund T. Andrzejczak was born in 1967 in Świdnica Śląska. He is a graduate of the Military Academy of the Armored Forces in Poznań, the Defense Academy of the Czech Army, the National Defense Academy in Warsaw, and the Royal College of Defense Studies in London.

On 2 July 2018, the President of the Republic of Poland appointed major general Andrzejczak to the post of the Chief of the General Staff of the Polish Armed Forces and promoted him to lieutenant general. On 12 November 2019, he got the promotion to the rank of general, the highest rank for officers in active service in Poland.

His personal awards include the Order of the Rebirth of Poland – Military Cross, Order of the Military Cross - Commander's Cross, Military Cross of Merit, Silver Medal of the Armed Forces in the Service to the Fatherland, Silver Medal for Merit for National Defense, Stars of Iraq and Afghanistan for his overseas service.