Immediately, he turned his back on it by launching, to everyone's surprise, a vigorous anti-corruption campaign.
The outgoing president has a good chance of being re-elected on August 24 in a poll that promises to be tense, although he has struggled to keep the promises of his first term, believe many observers.
Lourenço leads the MPLA, the party in power since independence in 1975. In 2017, he succeeded comfortably with 61% of the vote to Dos Santos, the strongman for 38 years, accused of having largely diverted the resources of the country rich in oil for the benefit of his relatives.
The ex-artillery general trained in the USSR had promised radical reforms but poverty remains glaring, in a climate of galloping inflation.
"The popularity of the MPLA is low, especially in the cities," said Borges Nhamirre, of the Institute for Security Studies (ISS) in Pretoria. Lourenço "had promised more transparency, less corruption. Today, his governance is perceived as authoritarian".
Joao Manuel Goncalves Lourenco, originally from Lobito (west), fought in his youth against Portugal. After independence, he took part in the interminable civil war (1975-2002) which broke out between the MPLA government and the rebels of Unita, which has now become the main opposition party.
Like many rising leaders during decolonization, he was educated in the Soviet Union. He became political leader of the military wing of the MPLA during the Civil War, a Cold War conflict that saw Cuba support the MPLA while CIA-backed militias fought it.
Having become governor of the province of Moxico (east) in the 1980s, he quickly rose through the ranks within the MPLA, leading its parliamentary group before becoming vice-president of Parliament.
- Poverty, inflation, drought -
It is paradoxically his ambition that fails to put an end to his career. Unable to hide his desire to succeed Dos Santos, at the turn of the years 1990-2000, the latter put him on the sidelines.
After years of political purgatory, he emerged from hibernation and was appointed defense minister in 2014, before being named Dos Santos' successor.
As soon as he was elected in 2017, he quickly turned against his predecessor and launched a vast "clean hands" operation to recover the billions embezzled by the Dos Santos clan.
Inheriting an economy dependent on oil and in recession, he set up an ambitious reform plan aimed at varying the sources of income and privatizing public enterprises.
"The problem is that the majority of the population has not benefited from these reforms," said Marisa Lourenço, an independent political analyst based in Johannesburg. Many of the 33 million Angolans are struggling to feed themselves, facing inflation but also the worst drought in 40 years.
Many now view the anti-corruption campaign as selective and politically motivated, fueling divisions within the ruling party.
The death of Dos Santos in July further plagued President Lourenço, sparking a public feud with several of his children.
However, the change of course compared to the old regime has been welcomed abroad where its reputation remains rather solid.
Lourenco recently mediated talks between Kinshasa and Kigali amid escalating tensions between those neighbors.
During the launch of his election campaign last month, he notably promised new hospitals and better transport.
He is married to Ana Dias Lourenco, a former minister who also represented Angola at the World Bank. They have six children.