Muhyiddin grew up in the state of Johor and joined the state public service after graduating from university. He assumed management positions at various state-owned companies.
In the 1978, he was elected as Member of Parliament for Pagoh. During his term as MP, he was appointed Deputy Minister of Federal Territories and later Deputy Minister of Trade and Industry. As Johor UMNO chief, he was Menteri Besar of Johor from 1986 to 1995.
He returned to federal politics in 1995 and was appointed to the Cabinet as Minister of Youth and Sports. He was appointed Minister of Domestic Trade and Consumer Affairs after the 1999 general election and became a vice-president of UMNO in 2000. Under the premiership of Abdullah Ahmad Badawi, Muhyiddin served as Minister of Agriculture (2004–2008) and then Minister of International Trade and Industry (2008–2009).
In 2008, he contested and won the UMNO deputy presidency and was appointed Deputy Prime Minister and Minister of Education by Prime Minister Najib Razak in 2009. As Education Minister, Muhyiddin ended the use of English as the medium of instruction for science and mathematics in public schools. He also attracted controversy after describing himself as "Malay first" when challenged by the opposition to pronounce himself as "Malaysian first." During Najib's mid-term Cabinet reshuffle in July 2015, he was dropped from his position, marking the first incumbent to be left out; in June 2016 he was sacked from UMNO.
Muhyiddin was born in Muar, Johor, Malaysia. His father, Muhammad Yassin bin Mohammad, was of Buginese descent. Muhammad Yassin was an Islamic theologian and cleric based in Bandar Maharani, Muar, Johor, while his mother, Hajjah Khadijah Kassim, was Javanese.
Muhyiddin received his primary education at Sekolah Kebangsaan Maharani, Muar, Johor and Sekolah Kebangsaan Ismail, Muar, Johor. He received his secondary education at the Muar High School, Johor. Subsequently, he attended Universiti Malaya, Kuala Lumpur and received an Honours bachelor's degree in Economics and Malay Studies in 1971.
After the completion of his studies, Muhyiddin joined the Johor state public service as the Assistant Secretary of Training and Scholarship. In 1974, he was appointed the Assistant District Officer (ADO) of Muar. He left the civil service to join the corporate sector in the Johor State Economic Development Corporation (PKENJ), managing its subsidiary companies like Sergam Bhd as Managing Director (1974–1977), Equity Mal (Johore) Sdn Bhd as Director (1974–1978), Sri Saujana Bhd as Managing Director (1974–1978) and SGS Ates (M) Sdn Bhd as Human Resource Manager (1974).
Muhyiddin's involvement in politics began when he joined UMNO as ordinary member at the Pagoh division in 1971. He was elected as UMNO Youth Chief of the Pagoh division and the Secretary in 1976. Later he became Youth Chief of Johor state UMNO Youth until 1987.
Muhyiddin occupied the seats of Exco in the national Malaysia UMNO Youth. In 1984, Muhyiddin was elected the UMNO Division Chief of Pagoh replacing Tan Sri Othman Saat. Muhyiddin rose up the ranks and file of Johor UMNO quickly. From being a state executive council member, he rose to become Johor UMNO's head and later became Menteri Besar of Johor.
Muhyiddin contested and was elected Member of Parliament for the Pagoh constituency in the 1978 general election and kept the seat until 1982. Muhyiddin was appointed Parliamentary Secretary in the Ministry for Foreign Affairs; subsequently he was promoted to Deputy Minister in the Ministry of Federal Territories and later the Ministry of Trade and Industry. In the 1986 general election, Muhyiddin contested and won the Johor State Legislative constituency seat of Bukit Serampang, opening the path for him to become the Menteri Besar of Johor on 13 August 1986.
His tenure as Menteri Besar lasted until 6 May 1995.
Muhyiddin returned to contest the Pagoh parliamentary seat in the 1995 General Election.
He served several different federal government cabinet posts as Minister of Youth and Sports (1995–1999), Minister of Domestic Trade and Consumer Affairs (1999–2004), Minister of Agriculture (2004–2008) and Minister of International Trade and Industry (2008–2009). He was appointed Deputy Prime Minister, and Minister of Education, by Prime Minister Najib Razak in 2009.
In 1984, Muhyiddin contested a UMNO Supreme Council seat but lost. Muhyiddin was later appointed as the UMNO Johor State Liaison Chairman and next appointed as Supreme Council member. In November 1990 he was a candidate for the UMNO vice-presidency, but lost again. Muhyiddin attempted again in the November 1993 UMNO party election, successfully this time. But he lost the 1996 election when defending the vice-president post. Eventually, in the election in 2000, he again won the post of vice-president of UMNO, remaining in that post until the October 2008 party election, when Muhyiddin successfully sought the higher post of deputy president, which was left vacant as the incumbent, Najib Razak (who was acting party president after the retirement of Abdullah Ahmad Badawi), became UMNO president.
Muhyiddin attacked Abdullah Ahmad Badawi's original transition plan as "too long", and some people say that at one point Muhyiddin was about to ask and force Abdullah to quit, though he never did so directly. During the 2008 general election, Muhyiddin managed to keep his seat and remained as an UMNO leader. Shocked by the election results, he called for reforms.
During the 2009 UMNO General Assembly and party election, Muhyiddin was a candidate for the deputy president post which was vacated by the incoming Prime Minister Najib Tun Razak. He was challenged by Mohd Ali Rustam, Malacca Chief Minister, and Muhammad Muhammad Taib, Rural and Regional Development Minister. Muhyiddin, seen as a supporter of Mahathir Mohamad, was seen to be the front-runner for the race, garnering many nominations by the UMNO divisions. But the competition was tough, as Taib and Rustam gained more ground especially from the Badawi camp. The race was tipped by political analysts to be very tight. However, the UMNO supreme council decided to disqualify Ali Rustam's candidacy after his assistants were caught involved with corruption after an investigation. The election resulted in Muhyiddin's election to the post with 1,575 votes to Muhammad Taib's 916.
Muhyiddin was appointed as the Deputy Prime Minister on 9 April 2009, when Najib took over from Abdullah Ahmad Badawi and unveiled his first Cabinet.
Continuing as Minister for Education, he announced the decision to return to the teaching of mathematics and science in Malay in all government primary and secondary schools.
Muhyiddin waded into controversy in March 2010 by stating he was "Malay" first rather than "Malaysian first". He also said that there is nothing wrong with other races doing the same; for example, the Chinese could claim themselves to be "Chinese first, Malaysian second" and same for the Indians. On 13 July 2010 he said that anyone was free to form an association, including Chinese or Indian versions of the Malay rights group Perkasa. Prime Minister Najib came to Muyyiddin's defence, denying that his statement was inconsistent with the "1Malaysia" concept promoted by the government.
During Najib's mid-term Cabinet reshuffle on 28 July 2015, he was dropped from his position as Deputy Prime Minister. The dismissal came after Muhyiddin had made public and critical remarks about Najib's handling of the 1Malaysia Development Berhad scandal. Najib stated that Muhyiddin's dismissal, and the contemporaneous dismissals of other Ministers who had been critical of his leadership, was to create a more "unified team". Muhyiddin remained UMNO vice president, but after keeping up criticism of UMNO, he was eventually sacked by the party's supreme council in June 2016. Muhyiddin remained unrepentant, maintaining that he had never betrayed the party, and pledging to continue speaking out.
In August 2016, Muhyiddin registered a new political party, called Parti Pribumi Bersatu Malaysia (or Bersatu for short) together with former Malaysian Prime Minister Mahathir Mohammad. Muhyiddin became the party's president while Mahathir and his son Mukhriz became the chairman and vice-president respectively. The new party is focused on bumiputeras – Malays and Orang Asli – in the sense that full membership is only open to bumiputeras. Other races can join the party, but cannot vote or contest in party elections. Mahathir later tipped Muhyiddin to become Prime Minister if the opposition wins the next Malaysian general election.