The parade marked the 75th anniversary of the Workers' Party.
Correspondents say that previously unseen "massive" long range ballistic missiles were displayed. North Korea typically uses its parades to show off new missiles and weaponry.
It is the country's first parade in two years and comes just weeks ahead of the US presidential election.
North Korea had not featured ballistic missiles in its parades since President Donald Trump and Mr Kim held their first summit in 2018.
According to South Korea's military, the parade took place before dawn on Saturday. The reason for its early timing is not yet known.
No foreign media or foreigners were allowed to attend, so analysts are relying on edited state-media footage which is being released to assess the parade.