An analysis of the vaccine also found it to be effective, 66%, at preventing moderate to severe Covid-19 infection.
In trials, there were no Covid-19 linked deaths, the FDA said, adding its independent panel of experts will meet on Friday to discuss the analysis.
Approval of the vaccine is not certain but likely given the pattern for other vaccines that have received US emergency use approval for Covid-19.
Johnson & Johnson said its vaccine was also effective at preventing asymptomatic infections with an 88% efficacy rate compared to a placebo group.
The pharma group said this suggests inoculations with its candidate would be a major help in stopping the spread of the disease.
J&J’s global trial involved nearly 44,000 people with 72% effectiveness among US participants and 57% in South Africa, where the vaccine has already been approved.
Side effects included headaches, fatigue and myalgia but only three people had severe incidences and the FDA said its analysis raised no concerns that would stop an emergency use authorisation.
J&J’s Belgian subsidiary Janssen has developed the vaccine and it has already received orders for 30mln doses from the UK, 100mln for the US and Canada 38mln.
Janssen is investigating whether two doses of the jab would be more effective especially against new variants of Covid-19, such as the South African variety.
Shares in J&J rose 0.9% US$161.82.