The Emnid poll, commissioned weekly by the Bild am Sonntag newspaper, showed the FDP gaining one point over last week's survey and reaching five percent - the hurdle needed by parties to get parliamentary representation.
The poll, from the respected opinion research institute, is good news for the FDP as it comes just one week before key state elections in Schleswig Holstein and two weeks before similar elections in North Rhine-Westphalia.
Under German law, parties who do not obtain a minimum of five percent of the vote are not allowed to send representatives to parliament.
The poll also showed a one-point gain for Chancellor Angela Merkel's Christian Democratic Union party, with the CDU reaching 35 percent this week. Rumours have been flying that Merkel was preparing to ditch the FDP as governing partners if they fail to clear the five percent hurdle at the state elections.
Both the Social Democratic Party and the Pirate party lost one point, with the SPD now at 26 percent and the Pirates at 11 percent. The Greens and the Left party stayed the same as the previous week, with 13 percent and seven percent respectively. Other parties accumulated a total of three percent.