Williamson, 22, was a race winner in the GP3 Series in 2011 with the MW Arden team. He switched to the Formula Renault 3.5 Series for 2012, but now makes his GP3 return.
He will join Filipino-Swiss Marlon Stockinger and fellow Briton Alice Powell in the Status GP line-up for Hockenheim. He replaces Japanese racer Kotaro Sakurai, who has experienced sponsorship problems.
Before racing in GP3, Williamson finished as runner-up in the 2010 Formula Renault UK Championship, before winning the prestigious McLaren Autosport BRDC Award, for which he gained a prize test in a McLaren Formula 1 car.
On GP3’s last visit to Hockenheim, in 2010, Status GP’s Robert Wickens scored a race win in the feature race and also claimed the fastest lap.
Status GP team manager Paul Bellringer said: “Lewis is the ideal replacement to step into our driver line-up this weekend. He already knows the GP3 car from last season, and is very talented. Status GP has long admired his ability and we’re looking forward to working with him in Germany."
Williamson added: "I’ve known some of the guys at Status GP for a couple of years, and this is a great opportunity. I know I’ve got to put everything I’ve got into it at Hockenheim this weekend and make sure we do everything right. We just need to progress through free practice, qualifying and then the two races and see what comes of it.
“It’s nice to race with Marlon and Alice. I know both of them from our days in Formula Renault UK, so I’m sure we will get along well and work strongly together."