The 27-year-old defender has already passed a medical in Lower Saxony and is immediately available for new coach Tayfun Korkut, whose side made a winning start to 2014 with victory at Wolfsburg last weekend.
"This opportunity suddenly arose for us to do this loan deal and now we have another option for our right full-back position with a lot of European experience," said Hannover director of sport Dirk Dufner.
Rajtoral will provide cover at right-back for the team captain Steven Cherundolo, who has been struggling with a knee injury for much of the season, spending just 82 minutes on the field after an operation last year.
"I'm really looking forward to playing in the Bundesliga and I'm delighted now to be a Hannover player," said Rajtoral.
"I will give everything for the best possible success of the team.
"Of course I followed the Bundesliga avidly in the Czech Republic and I know how popular Jiri Stajner was among Hannover fans. That was also a reason to join."