The 63-year-old German leader scored around 33.5 percent of the vote with her conservative Christian Union (CDU/CSU) bloc, according to CNN.
This puts her on track to match the post-war record of 16 years in office held by late Helmut Kohl.
The Social Democrats (SPD) and its candidate Martin Schulz, was seen trailing far behind, with 20-21 percent support.
The anti-immigration Alternative for Germany (AfD) won 13 percent of the vote; this may come out with a result that will bring a far-right party into parliament for the first time in more than half a century.
Merkel has pledged to reduce Germany's already low unemployment, and is offering modest tax cuts. She also defended her 2015 "open door" policy that led to more than a million refugees entering the country and stated that the events of that year must not be repeated.
On that note, Merkel stayed away from making big election promises, leading to accusation of "sleepwalking" through the campaign, by the German media.
Once the final results is out on Monday, coalition talks will begin.
To form a government, the parties involved must have a combined total of at least 50 percent of the seats in the parliament.
Parliament will reconvene on October 24, with the new government in place.(ANI)