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.
General Andrzejczak has begun his military service as platoon leader at the 2nd Infantry Regiment in Giżycko. Over the 1993-1996 he commanded a tank company of the 15th Mechanized Brigade. Then, for a period of two years he served in the reconnaissance and operations sections of the 4th Armored Cavalry Brigade.
Between 1998-1999 general Andrzejczak served as chief of staff and 2001-2003 as deputy commander of the Lithuanian-Polish Peace Force Battalion (LITPOLBAT). In 2003-2005 he commanded the 1st Krechowiecki Lancers Armored Battalion of the 15th Mechanized Brigade and in 2003-2006 he was the deputy chief of the G-3 Operations Branch of the Land Forces Command. For the next 4 years, during the overseas combat missions, he held the posts of the Chief of Operations Branch in Iraq and the Commander of the Polish Task Force White Eagle/101st AA CJTF in Ghazni, Afghanistan over two rotations.
In 2008-2010 general Andrzejczak served in the capacity of the deputy commander of the 34th Armored Cavalry Brigade and in 2010-2012 as the assistant to the chief of staff of the 2nd Mechanized Corps. In 2011 he was promoted to the rank of brigadier general and in 2012 he took over command of the 17th Wielkopolska Mechanized Brigade. From 2014 general Andrzejczak was the Deputy Commander - Chief of Staff of the 12th Mechanized Division and in 2016 became the Commander of the 12th Division. On 15 August 2016 he was promoted to major general.
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.