The Frenchman has been banned for four years from all soccer-related activity for ethics violations and his replacement to head the sport's European governing body will be elected at the event in Athens.
The ethics committee of soccer's governing body said an exception had been made for Wednesday's event following a request from UEFA.
"UEFA formally asked the adjudicatory chamber of the independent ethics committee for an exception for Mr Platini to be able to make a short farewell address to its congress in Athens," said the committee in a statement.
"The chairman of the adjudicatory chamber, Mr. Hans-Joachim Eckert, granted this exception as a gesture of humanity."
One of the finest players of his generation who went on to become a powerful sporting official, Platini was suspended over his dealings with fallen world soccer chief Sepp Blatter during the scandal which shook the sport's global governing body last year.
Platini was banished along with former FIFA President Blatter over a payment of two million Swiss francs ($2.08 million) made to the Frenchman by FIFA with Blatter's approval in 2011 for work done a decade earlier.
FIFA's ethics committee said the payment, made at a time when Blatter was seeking re-election, lacked transparency and presented conflicts of interest. Both men denied wrongdoing.
Platini, who was first elected as UEFA president in 2007, had been favourite to replace Blatter at the time. Instead, his former general secretary at UEFA, Gianni Infantino was voted to the top job in February.
Dutchman Michael van Praag and Slovenian football boss Aleksander Ceferin are the only two candidates on Wednesday.
(Writing by Brian Homewood, editing by Pritha Sarkar)
