Having debuted at Manor, the young German has now lost his race seat after his second season in Formula 1 with Sauber.
Yet Wolff said recently that Wehrlein, 23, will continue to enjoy the backing of the Mercedes driver programme.
The Mercedes chief has now told Sport Bild: "We have supported Pascal since 2013 and he earned his chance in Formula 1 after his DTM victory in 2015.
"After that, he experienced two not so easy years in Formula 1 with Manor and Sauber.
"But we will keep him in our racing family in 2018 and also offer him a role as F1 test driver at Mercedes, to keep his door open to Formula 1 for 2019."
The best finish of Wehrlein's career so far was eighth in last year's Spanish Grand Prix.