HRS has bought up almost 62% of the shares in Germany-based accommodation service hotel.de.
Terms of the deal were not disclosed but HRS now holds a 64.6% stake in its Nuremberg-based counterpart which runs the hotel.de and hotel.info sites.
HRS had a small stake in hotel.de from a previous deal.
HRS offers more than 250,000 hotels in 180 countries to leisure and business travellers while hotel.de features 210,000 properties.
It is anticipated the deal will strengthen the market position of both brands and hotel.de will continue to operate as standalone company managed by its existing team.