Labourers earning about 100 Cuban pesos ($4.10; £2.13) a month will see their wages rise to 225 pesos from 1 May.
The move will benefit 1.6 million workers, including farmhands, plumbers and undertakers, who survive on the lowest wages in communist Cuba.
President Castro’s confidence in the economy has been buoyed by closer trade relations with Venezuela and China.
Oil deposits have also recently been discovered off Cuba’s coast.
Welfare gains
Many Cubans supplement their low wages by working on the black market.
Cuba’s economy has been struggling since the collapse in 1991 of its former backer, the Soviet Union.
However, Cuba’s government has recently introduced a number of measures in an attempt to improve the livelihood of its citizens.
“I think we are coming along rather well,” President Castro said in a televised address on Thursday, his eighth speech in 11 days.
At the end of March, the 78-year-old president announced a rise in payments for Cubans claiming welfare, including single mothers, widows and disabled people.
The increase in welfare payments, which will benefit 1.5 million Cubans, will also take place from 1 May.
President Castro said the minimum wage increases would cost the Cuban government about 1.1bn pesos.
The average Cuban government worker earns about 300 pesos a month, although most citizens pay no rent, while education and health care provision are also free.