It is believed that he will talk about "developments in the European Union, Brexit, direct democracy and how to make the impossible possible".
The event is reportedly being hosted by MEP Beatrix von Storch, a member of anti-immigrant party AfD, which has realistic aspirations to enter Germany's parliament for the first time in the country's election on 24 September.
Von Storch has been a member of the EFDD group in the European Parliament - which also includes Ukip - since being expelled from the ECR group in April last year.
Her expulsion followed comments in which she appeared to call on European border guards to use firearms to deter illegal immigrants. She later described the comments as a "tactical mistake".
In her Facebook post, von Storch reportedly said that Farage had been so impressed with the AfD's campaign in the German elections that he had accepted "without hesitation" her invitation to appear at a campaign rally.
Protesters are said to be planning to organise a counter-rally outside the Spandau Citadel while the Farage is giving his speech.
In its manifesto, AfD, which is currently polling between eight and 11 per cent, calls for a referendum on leaving the eurozone and for a British-style referendum on EU membership, unless the EU returns to being "a federation of sovereign states".
A majority of AfD members are thought to have welcomed the announcement of Farage's appearance, praising the Brit as a "straight-down-the-line" and "fiery" speaker.
But Richard Corbett, a member of Parliament's S&D group, was critical, telling this website, "Now that he thinks he's secured Brexit, Farage no longer hides his true colours."
Ukip, however, has denied that the event is being organised by the AfD.
On Friday, a party spokesperson told this website, "Nigel Farage is speaking in favour of Beatrix Von Storch, who is member of EFDD group, and a member of AfD."
The spokesperson went on, "It is not - as far as I know - an AfD conference, but has been organised by Von Storch."