Contracted to Saracens, he is currently on loan with the Stormers in South Africa and will join Connacht on a two-year deal at the end of the season.
The 5ft 11in, 102kg hooker has a wealth of experience in the number 2 jersey having played for Saracens in the English Premiership for the past two seasons.
This will not be Reynecke's first visit to the Sportsground. The 29-year-old was part of the Saracens squad that visited Connacht last August for a pre-season friendly.
Speaking about the move, he said: "I'm very excited at the prospect of going to Ireland, especially Galway.
"Connacht has shown this season they are serious about establishing a strong and successful rugby culture there, and I intend giving my all to contribute to the cause."
The province's head coach Eric Elwood added: "With Sean (Cronin) moving on at the end of the season, we needed cover at hooker and we are very pleased to sign a player of Ethienne's calibre, especially in such a crucial position.
"He is an experienced player who we are confident can offer a lot to Connacht."