The businessman made the pledge in a blog post in which he said his companies, which include travel and leisure, were in a "massive battle to survive".
He said COVID-19 was "the most significant crisis the world has experienced" in his lifetime, with his businesses employing more than 70,000 people in 35 countries.
The 69-year-old wrote: "Our airlines have had to ground almost all their planes; our cruise line has had to postpone its launch; our health clubs and hotels have had to close their doors and all bookings to our holiday company have stopped.
"Our people have and, will always be, my number one priority. It is their future job security and their well-being that I am 100 per cent focusing on, in these frightening and unprecedented times."
Sir Richard said recovery would "depend critically" on governments implementing the support programmes which they had announced.
The entrepreneur's pledge comes after he was criticised last week by Labour after Virgin Atlantic announced it told staff to take eight weeks of unpaid leave following a sharp drop in customers.
The airline said the move would "drastically reduce costs without job losses" with it adding that the cost to staff would be spread over six months.
Elsewhere, British Airways' chief executive has hinted at job cuts and said he will waive his salary for the next two months as the airline also struggles with the coronavirus crisis.
In a letter to all BA staff seen by Sky News, Alex Cruz said "of course job security is top of mind" and that the carrier is doing "everything we can to protect as many jobs as we can" during the COVID-19 crisis.
But he added that the company was "working hand in hand with [the unions] to look at all the options including the government employment assistance scheme".