Workers will organize the strikes around the two major consumption dates amid a growing row over wages, jobs and conditions.
The strikes around Black Friday November 25 and Cyber Monday November 28 were announced on Tuesday November 11.
It comes after the The Communications Workers Union (CWU) has withdrawn its strikes scheduled for November 12 and 14 after an inquiry from the post office.
— The CWU (@CWUnews) November 1, 2022
Royal Mail staff announce strike for Black Friday and Cyber Monday
The union said it now wanted to take more “proportionate” action.
Royal Mail made an offer on wages and conditions on Monday which was like a “handover document” because the union said it involved attacks on terms and conditions as well as redundancies.
The CWU will put the offer to its membership on a ballot and recommend rejection.
Members will also be asked to cast a vote of no confidence in Royal Mail chief executive Simon Thompson.
CWU General Secretary Dave Ward said industrial action will continue until Christmas unless the dispute is resolved.
What did the Royal Mail say about the strikes?
A Royal Mail spokesman said: “On Monday October 31, Royal Mail offered a new change-over offer to the CWU worth 9% over two years, despite losing £219 million to the first semester.
“The CWU has had talks with us at Acas and says they are open to change, but now they have to show it.
“Instead, the CWU has announced a four-day strike that will further harm our business at our busiest time of the year.
“The CWU is playing a dangerous game with its members’ jobs and the future of Royal Mail.
“We urge the CWU to withdraw these strikes for the benefit of our customers and staff.
“We apologize to our customers for the inconvenience the continued CWU strike will cause.
“We are doing everything we can to minimize delays and keep people, businesses and the country connected.”