More than 300 members will walk out for 48 hours from 00.01am on Monday 19 February 2024 until 11.59pm on Tuesday 20 February 2024, and again from 00.01am on Monday 4 March 2024 until 11.59pm on Tuesday 5 March 2024.
Among those taking action are security, station, revenue and control staff.
The announcement comes on the first day of a separate series of rolling strikes being organised by train drivers union, Aslef, which has shut down some of the busiest rail routes in the country.
The RMT said that Arriva Rail London, which has the contract on London Overground, has offered a below inflation pay offer, and that their members over overwhelmingly voted for a walkout.
Mick Lynch, general secretary of the RMT, said: “London Overground workers do an important job delivering services for Transport for London and supporting passengers on journeys throughout London.
“Our members are furious that they have been given a below inflation pay offer and want to see an improvement that represents the value they bring to the company.
“If this dispute cannot be resolved then RMT is more than prepared for a sustained period of industrial action to get London Overground workers the pay rise they deserve.”
The Independent has contacted the Department for Transport and Arriva Rail London for comment.
RMT members working on the London Underground were due to walk out earlier this monthbut the plane planned strikes were called after at the last minute after progress in talks with Transport for London.
From 30 January, train drivers belonging to Aslef are stopping work region-by-region over the course of a week between Tuesday 30 January and Monday 5 February. Thousands of trains will be cancelled on each day.
The effect is exacerbated by a nine-day ban on overtime running from 29 January to 6 February.