He passed studentexamen in Stockholm in 1932 and was commissioned as an officer in Fortifikationen ("Royal Engineers") in 1935 with the rank of second lieutenant.

[1] He was then promoted to major in the Swedish Engineer Troops and appointed head of the Army Staff's Equipment Department in 1953.

[4] In 1959, Wåhlin was promoted to lieutenant colonel and appointed commanding officer of the Swedish Army School of Field Works (Arméns fältarbetsskola, FältarbS) in 1959 and two years later he was promoted to colonel and appointed head of Section I of the Army Staff.

In 1964, Wåhlin was promoted to major general,[5] after which he served as Master-General of the Ordnance and head of the Royal Swedish Army Materiel Administration from 1 October 1964 to 30 June 1968.

From 1978, Wåhlin chaired the parliamentary commission that investigated issues concerning the future of the aerospace and missile industries.