Cuba's Communist Party has announced Miguel Díaz-Canel will succeed Raúl Castro as the party's first secretary.
Mr Díaz-Canel, who in 2018 succeeded Mr Castro as Cuba's president, had been widely tipped for the arguably more influential post of party leader.The transition means that the island will be governed by someone other than Fidel or Raúl Castro for the first time since the Cuban revolution in 1959.
Mr Díaz-Canel is seen as loyal to the Castros and their economic model.
Speaking on Friday, when Mr Díaz-Canel had not been officially named yet as first secretary, Raúl Castro said that he would hand over the leadership to a younger generation "full of passion and anti-imperialist spirit".
At 60, Mr Díaz-Canel is almost 30 years younger than his predecessor.
Communist Party delegates elected a new central committee on Sunday but the leadership positions were only revealed on Monday.
It follows the announcement on Friday - on the first day of the party's four-day congress - that Raúl Castro was stepping down from the key position of first secretary.The 89-year-old had been in the post since 2011, when he took over from his older brother, Fidel Castro.
Between them, the two brothers have ruled Cuba since the 1959 revolution which overthrew the authoritarian ruler Gen Fulgencio Batista.
Miguel Díaz-Canel represents a logical choice to succeed Raúl Castro.
President Diaz-Canel has shown himself as loyal to the Castro-model of state socialism in Cuba and - as Cuba's president - has only allowed a very limited expansion of the private sector, in line with his predecessor's wishes.
Politically, there is no likelihood of any sudden changes and it is clear that Mr Castro sees Mr Díaz-Canel as a safe pair of hands.
Raúl Castro wants to leave his final official role in the Cuban revolution with a sense of continuity, of passing the torch to a younger leader who holds the same values.
Given the bleak economic outlook, however, Mr Diaz-Canel may well have to further liberalise the centrally controlled economy in the very near future.
Fidel Castro was the country's leader from 1959. He fell ill in 2006 and two years later he formally handed over the presidency to his brother.
Fidel Castro died in 2016 but his brother Raúl maintained the grip of Cuba's Communist Party on power on the island.