The delivery giant said it will "temporarily" halt the deliveries on Saturdays from this weekend.
It said it will continue to provide its letter delivery service from Monday to Friday as normal and said customers "should continue to post both letters and parcels as usual on Saturday".
Royal Mail will continue to collect all mail from businesses, post offices and post boxes, it said.
Shane O'Riordain, managing director of marketing, regulation and corporate affairs at Royal Mail, said: "Our postmen and postwomen are working very hard across the UK in challenging conditions.
"As we said at the start of the coronavirus crisis, there will be some disruption to services.
"We understand the importance of the postal service in keeping the UK connected at this time.
"We have also listened to our hard-working colleagues who have asked us to ease the additional burden on them if possible. As a result, we are making some temporary changes to postal services."
Royal Mail said it has been in dialogue with the Government and regulator Ofcom throughout the crisis and will keep the temporary change to postal arrangements under review.
The move was criticised by the Communication Workers' Union (CWU), which represents postal workers.
A CWU spokesman said: "We will be seeking urgent discussions with the Government on this issue.
"The reduction of the Universal Service Obligation was a key factor in our live national strike ballot.
"The last thing we want to do is call strike action at this point but we will not sit back and see our members' jobs put at threat and the service to the public worsened."
Last month the union called for households' deliveries to be cut to three days a week due to coronavirus.