Manley instituted a series of socio-economic reforms that yielded mixed success. Manley's successful trade union background helped him to maintain a close relationship with the country's poor, black majority, and he was a dynamic, popular leader. Manley moved easily among people of all strata and made Parliament accessible to the people by abolishing the requirement for men to wear jackets and ties to its sittings. In this regard he started a fashion revolution, often preferring the Kariba suit which was a type of formal bush or safari jacket with trousers and worn without a shirt and tie.

In diplomatic affairs, Manley believed in respecting the different systems of government of other countries and not interfering in their internal affairs.

Manley was the Prime Minister when Jamaica experienced a significant escalation of its political culture of violence. Supporters of his opponent Edward Seaga and the Jamaica Labour Party (JLP) and Manley's People's National Party (PNP) engaged in a bloody struggle that began before the 1976 election and ended when Seaga was installed as Prime Minister in 1980. While the violent political culture was not invented by Seaga or Manley, and had its roots in conflicts between the parties from as early as the beginning of the two-party system in the 1940s,

In response to a wave of killings in 1974, Manley oversaw the passage of the Gun Court Act and the Suppression of Crime Act, giving the police and the army new powers to seal off and disarm high-violence neighbourhoods. The Gun Court imposed a mandatory sentence of indefinite imprisonment with hard labour for all firearms offences, and ordinarily tried cases in camera, without a jury. Manley declared "There is no place in this society for the gun, now or ever.

During his period of opposition in the 1980s, Manley, a compelling speaker, travelled extensively, speaking to audiences around the world. He taught a graduate seminar and gave a series of public lectures at Columbia University in New York.

In the 1980s a Judicial Enquiry, the Smith Commission, was held on the 1976 State of Emergency. Manley admitted that he declared it on evidence that was manufactured to help him win the forthcoming election.

In 1986 Manley travelled to Britain He attended a number of venues including the Afro Caribbean Resource Centre in Winston Green. The mainly black audiences turned out en masse to hear Manley speak.

By 1989 Manley had softened his socialist rhetoric, explicitly advocating a role for private enterprise. With the fall of the Soviet Union, he also ceased his support for a variety of international causes. In the election of that year he campaigned on a very moderate platform.

Manley's second term was short and largely uneventful. In 1992, citing health reasons he stepped down as Prime Minister and PNP leader. His former Deputy Prime Minister, Percival Patterson, assumed both offices.