Lam was elected president -- the number two position in Vietnamese politics -- by the National Assembly on Tuesday, unifying leadership of the party and state as Xi did in China.
"Vietnam's General Secretary and President To Lam would visit China between April 15-17," the official told AFP, adding he will meet with Xi.
Other media reports have said the trip will begin on April 14.
Despite rival territorial claims in the South China Sea, the two socialist states have sought to deepen already close economic ties to guard against global trade upheaval instigated by US President Donald Trump's tariffs.
Both Vietnam and China get much of their oil imports via the Strait of Hormuz, where shipping has largely been halted due to the US-Israeli war with Iran.
Xi on Tuesday congratulated the Vietnamese leader on becoming president and expressed his willingness "to work with To Lam... to continuously strengthen our respective socialist causes", Chinese state media reported.