The former US President will travel to Germany for the launch of a summer of special events to mark the 500th anniversary of the Protestant church.
He will arrive in Germany on the same day as his successor Donald Trump is due in Brussels for a meeting with other NATO leaders – the first scheduled foreign visit for the President since taking office.
Mr. Obama is due to give a speech in the German capital and take part in a discussion on democracy with Ms. Merkel, who he once called his “closest ally”.
He and Ms. Merkel will speak on a purpose-built stage at the historic Brandenberg Gate, Berlin’s most prominent monument, which stands as a symbol of the Iron Curtain and the end of the Cold War when Germany was divided into East and West by the Berlin War.
In 2008, Ms. Merkel intervened to prevent then presidential candidate Obama from delivering a speech at the Brandenberg Gate because she said she thought it would be inappropriate to use the non-partisan symbol for political purposes – although he was permitted to speak at the monument as President in 2013.