Otan (Fatherland) members cast their ballots in favor of joining forces with Asar (All Together), led by Dariga Nazarbayeva, at conference in the Central Asian republic's capital, Astana.
"Delegates voted unanimously for the Otan-Asar unification," said Bakhytzhan Zhumaglov, the acting chairman of Otan. "The leader [of the new party] will be Nursultan Nazarbayev."
Deriga Nazarbayeva, who is a member of parliament and is seen by many as the frontrunner for the presidency when her 65-year-old father's seven-year term expires in 2014, is known as a proponent of a strong ruling party.
On June 19, Nazarbayeva said the new party should comprise political and, above all, "intellectual resources" from pro-presidential groups.
"It should be a truly ruling party," she said.
Her father has been in power in oil-rich Kazakhstan since the last years of the Soviet Union and the republic has avoided radical political changes that rocked many of the post-Soviet nations, including neighboring Kyrgyzstan, in recent years.
But the opposition in Kazakhstan has criticized the leadership over its allegedly poor record on democracy and freedom. The president's daughter has been accused of influencing public opinion via a media holding she purportedly controls.
Several amendments to existing legislation will have to be made before the party merger is legally recognized.