The 31-year-old's current contract is due to expire during the summer, which had resulted in speculation that he could depart, with AC Milan and Manchester United both said to be interested in his services.
However, the former Chelsea centre-back has insisted that he is "very happy in Paris".
"I am very happy in Paris and it's almost certain for me to renew the contract," he told Globo Esporte. "I believe that in one or two weeks I'll sign the agreement to extend my contract for another year."
Alex joined PSG from the West Londoners back in 2012.