Struber took over at Ashton Gate in June after Liam Manning, who had taken the club into the play-offs, left to take charge at Norwich City.
The Austrian, 49, spent a year managing Barnsley from 2019 to 2020 before spells at New York Red Bulls, Red Bull Salzburg and Cologne and had agreed a deal until the summer of 2028.
He had recently been critical of the volume of talent within the club’s academy and had voiced frustration over the January sales of Vyner and Mehmeti.
“I would like to thank Gerhard and Bernd for their hard work over the past nine months and we wish them all the best,” City chief executive Charlie Boss said.
“Roy’s appointment is about more than the results of the next seven games.
“Over the remainder of the season, he will help us set the standards and values at the club that we will need to be successful going forwards.
“Roy is a vastly experienced coach who has achieved and won at the highest level. He will support me, our players and our football staff as we build towards achieving our potential.
“We are in the process of appointing a sporting director who will have a direct input into the recruitment of a new permanent head coach.”