Tunku Ismail was born on 28 October 1894 at Istana Semayam, Johor Bahru and was the eldest son of Tunku Ibrahim (later Sultan Ibrahim) by his first wife, Sultanah Ungku Maimunah binti Ungku Abdul Majid. He was made the Tunku Mahkota of Johor on 2 November 1895, when Tunku Ibrahim was installed as the Sultan of Johor following Sultan Abu Bakar's death. He spent several years in Perak, where he was enrolled into the Malay College Kuala Kangsar. In March 1912, Tunku Ismail was sent to England to receive his tertiary education in a boarding school; his brothers Tunku Abu Bakar and Tunku Ahmad later followed suit.
Tunku Ismail was made the state's regent to take care of state affairs in 1928 as Sultan Ibrahim began to spend more time travelling overseas. In 1937, Tunku Ismail appointed a state executive councillor and a family acquaintance, Onn Jaafar as his private secretary and entrusted him to run the Johore Pavilion at the world fair in San Francisco the following year. Upon Onn's return from San Francisco, Tunku Ismail invited Onn to resume his former duties, which he accepted. Shortly before the Japanese armies occupied Johor during the Japanese Invasion of Malaya, Tunku Ismail fled to England for fear that the Japanese military government may manipulate him onto the throne in his father's stead.
Tunku Ismail returned to Johor after the war and was confronted with Malay nationalist movements which had erupted as a result of the rulers' dissatisfaction with the Malayan Union scheme. While Sultan Ibrahim faced widespread criticisms from the Malay grassroots and nationalist leaders due to his initial willingness to sign the Malayan Union scheme treaties with Sir Harold MacMichael, Tunku Ismail maintained a neutral relations between the British government and the Malay nationalist leaders. Nevertheless, Tunku Ismail officiated the opening ceremony of the United Malays National Organisation's (UMNO) first congress which was held at Istana Besar in May 1946 while Sultan Ibrahim was residing in London.
Tunku Ismail took over the responsibility to state affairs during the late 1940s and 1950s, and presented upon his father's behalf at official functions. On 27 August 1957, Tunku Ismail was one of the nine royal signatories at the royal signing ceremony of the Malaya's Federal Constitution. Nevertheless, he faced mild opposition from a few nationalist leaders in Johor, notably Ungku Abdullah, the party leader of Persatuan Kebangsaan Melayu Johor (PKMJ), a nationalist party that advocated Johor's secession from Malaya. A few days before signing the Federal constitution, Ungku Abdullah cabled to Sultan Ibrahim to boycott the signing ceremony, who notified Ungku Abdullah that he had since delegated the state's executive powers to Tunku Ismail. Ungku Abdullah called for Tunku Ismail to boycott the signing ceremony, who quickly turned down his calls.
Tunku Ismail succeeded his father as the Sultan of Johor on 8 May 1959. He was crowned at Throne Room of the Istana Besar, Johor Bahru on 10 February 1960. The Sultan was known to be very close to his subjects; he made annual trips to visit selected villages in all eight districts of Johor and frequently acquainted himself with the civil servants working for the state government.
On 10 August 1961, he stripped his eldest son Tunku Mahmood Iskandar, of the post of Tunku Mahkota due to misconduct–although he was given the post of Raja Muda on 1 December 1966. His second son, Tunku Abdul Rahman (1933–1989) became the Tunku Mahkota instead. However, shortly before his death in April 1981, Sultan Ismail reappointed Tunku Iskandar as the Tunku Mahkota, who succeeded him the following month.
A meek and quiet ruler by nature, Sultan Ismail was an animal lover and was instrumental in the setting up of the Johor Zoo. He also had a collection of wild animals ranging from deers to crocodiles. Among the Chinese community in Johor, he was known affectionately as "Lau Sultan", literally meaning "an old or elderly Sultan".
Sultan Ismail married twice. Both wives served as Sultanahs of Johor. They were:Sultanah Ungku Tun Amina binti Ungku Ahmad (d. 1977), a second cousin of the Sultan, married on 30 August 1920. Sultanah Aminah died in a road accident in 1977. He had seven children with her, of which only three survived to adulthood:
Tunku Abdul Jalil (born 1924-1925)
Tunku Kalthum Maimunah (born 1927-1930)
Tunku Abdul Rahman (born 1930-1930)
Tunku Mahmud Iskandar (Sultan of Johor) (born 1932-2010)
Tunku Abdul Rahman (born 1933-1989)
Tunku Helen (born 1936-1937)
Tunku Tun Maimunah (born 1939-2012)
Sultanah Tengku Nora binti Tengku Panglima Raja Ahmad, member of the Kelantanese royal household, married in October 1978. She is the sister of Tengku Zanariah (next Sultanah), the spouse of Sultan Iskandar.
He was the first Chancellor of Universiti Teknologi Malaysia when the institution was established in 1975.
In August 1977, both Sultan Ismail and his wife, Ungku Tun Aminah binti Ungku Ahmad, met with a car accident in Kulai. While she was permanently left in a vegetative state until her death a month later owing to brain damage, the sultan escaped with only minor injuries. Nevertheless, the ordeal passed rather quickly, and Sultan Ismail remarried in November 1977 to Tengku Nora. Tengku Nora was subsequently crowned as Sultanah the following October.
Sultan Ismail died on 10 May 1981 at the Hospital Sultanah Aminah, Johor Bahru at the aged 86 and was interred at the Mahmoodiah Royal Mausoleum, Johor Bahru.
Several institutions and places were named after Sultan Ismail, including:Jalan Sultan Ismail, formerly known as Treacher Road until 2007, in Kuala Lumpur
Sultan Ismail Bridge, Muar
Sultan Ismail International Airport, Senai
Perpustakaan Sultan Ismail, Larkin
Masjid Sultan Ismail, Universiti Teknologi Malaysia
Sultan Ismail Specialist Hospital, Taman Austin Perdana, Johor Bahru
S.M.K. Sultan Ismail, Johor Bahru
Bangunan Sultan Ismail, Kota Iskandar, Iskandar Puteri.
28 October 1894 – 2 November 1895: His Highness (Yang Amat Mulia) Tunku Ismail ibni Tunku Ibrahim, The Raja Muda of Johor
2 November 1895 – 8 May 1959: His Highness (Yang Teramat Mulia) Tunku Sir Ismail ibni Sultan Sir Ibrahim, The Tunku Mahkota, Regent of Johor
8 May 1959 - 10 May 1981: His Royal Highness (Duli Yang Maha Mulia) Sultan Ismail ibni Almarhum Sultan Sir Ibrahim, The Sultan of Johor
Malaya : Grand Commander of the Order of the Defender of the Realm (1958)
Grand Officer of the Order of the Star of Romania - 16 July 1920
Grand Cross of the Order of the Crown of Thailand - 21 July 1925
Companion of the Order of St Michael and St George (CMG) - 1 January 1926
King George V Silver Jubilee Medal - 6 May 1935
Knight Commander of the Order of the British Empire (KBE) - 11 May 1937
King George VI Coronation Medal - 12 May 1937
Grand Officer of the Order of the Crown of Italy - 1938
Queen Elizabeth II Coronation Medal - 2 June 1953
His son, Sultan Iskandar, the fourth Sultan of modern Johor applied the appellation of Al-Khalidi to his posthumous name. Hence he is referred to as Almarhum Sultan Ismail Al-Khalidi ibni Almarhum Sultan Sir Ibrahim Al-Masyhur.