NLD – the party led by Noble peace laureate and democracy campaigner Aung San Suu Kyi who still remains under house arrest - had its offices closed last year after a military crackdown.
"Officials informed us that we can re-open our headquarters effective this morning," Than Tun, a member of the NLD's executive committee said on Saturday.
Suu Kyi was detained and NLD offices shut on 30 May last year.
The military authorities in Yangon has been under international pressure since then to end the crackdown, release hundreds of political prisoners and move towards democracy.
The military, which has ruled the country since 1962, announced a "road map to democracy" last August, starting with fresh talks on a new constitution due to begin on 17 May.
The NLD has refused to consider joining the talks until Suu Kyi and party vice chairman Tin Oo are freed from house arrest.
Suu Kyi had led the NLD to a landslide victory in 1990 general elections, but the military refused to hand over power and annulled the results.