Born at Istana Anak Bukit near Alor Star as Tunku Abdul Halim, he was the second, but eldest surviving son, of Sultan Badlishah (born 1894; reigned 1943–1958), who later became the 27th Sultan of Kedah. His mother was Tunku Sofiah binti Tunku Mahmud (born 1910), who died in an automobile accident on 28 February 1935. Tunku Abdul Halim's maternal grandfather, Tunku Mahmud, was once Raja Muda or heir presumptive to the throne of Kedah.
He was educated at Alor Merah and Titi Gajah Malay schools and Sultan Abdul Hamid College in Alor Star between 1946 and 1948. He went on to Wadham College, Oxford and obtained a Diploma in Social Science and Public Administration. He subsequently joined the Kedah Administrative Service, serving in the Alor Star district office and later, the state treasury.
On 6 August 1949 he was appointed Raja Muda or heir apparent and succeeded as twenty-eighth Sultan of Kedah on his father's death on 15 July 1958. He was installed at the Balai Besar in Alor Star on 20 February 1959