With 99% of the votes counted in Tuesday's vote, the Liberal Conservative bloc, which includes the PM's Liberal Party, the nationalist Danish People's Party, and the Conservative Party, has won a majority in the 179 seat parliament.
"Today is a good day for Denmark. It is the first time in the country's history that a government led by the Liberal Party has been elected for a third term," Rasmussen said.
Rasmussen's Liberal Conservative bloc, offering tighter immigration laws and tax cuts, was closely pushed by the center-left Social Democrat-led opposition. The Social Democrats have pledged to improve the welfare system.
Mr Rasmussen's bloc will now have to make up its mind whether to include the New Alliance party, headed by Naser Khader, a Syria-born Palestinian immigrant.
The recently-formed party won five seats and Khader, who is also a karate black belt, has pledged to try to lessen the influence of the Danish People's Party hard-line leader Pia Kjaersgaard over the prime minister.
Eight political parties have overcome the 2% margin to make it into the legislature. The turnout was 86.5%, slightly higher than at the previous poll in 2005.
