The poll by ARD television revealed that the CDU/CSU bloc secured 42.5 percent with 302 seats in a 598-seat lower house of the parliament without Merkel's junior coalition partner Free Democrats (FDP) and the anti-euro Alternative for Germany (AfD).
According to the ARD poll, the FDP failed to retain its seats in the parliament with a disappointing result of 4.6 percent. The AfD scored 4.9 percent.
"This is the bitterest moment since the founding of the FDP, we should reshape ourselves from tomorrow," general secretary of FDP Christian Lindner said.
It showed the largest opposition party the center-left Social Democrats (SPD) took 25.6 percent of votes. The Green party, the SPD's favored ally, captured 8.0 percent. The Left Party got 8.0 percent of votes.
"We had expected more, the results is a big victory for the CDU/CSU", SPD's chairman Sigmar Gabriel said.
Earlier, a smiling Merkel dressed in blue told chanting supporters in her party headquarters in Berlin that her party had won a "super victory".
"This is a super result," said Merkel. "Tonight we could celebrate."
"Together we will do everything in the next four years to again make them successful years for Germany," Merkel said.
The latest results meant Merkel's conservative bloc could rule the country alone, which occurred only once in the Federal Republic's history under former chancellor Konrad Adenauer in 1957.
According to the poll, the Alternative for Germany (AfD), the election wild card which was founded seven months ago and calls for "orderly dissolution of the euro", garnered 4.9 percent of votes.
The party has thus become an uncertain element on the future German political landscape as all sides are waiting for the final official tally to see whether the party can overcome the threshold of 5-percent minimum threshold.
The official provisional results will be announced early in Monday morning.
If the anti-euro party enters the parliament, it could lead to a few weeks' horse-trading before the expected forming a "grand coalition" between CDU and the center-left SPD.
Merkel chaired such a grand coalition during her first term in 2005-2009, with SPD's chancellor candidate Peer Steinbrueck serving as her finance minister.
"We are still waiting for the final result. It's too early to say how we should proceed," said the chancellor, "We will discuss the issue in committees tomorrow, but tonight we can celebrate."
Xinhuanet
