Mumtaz Qadri, 26, who has already admitted gunning down Taseer outside a restaurant in Islamabad on January 4, was indicted on a murder charge during in-camera proceedings at Adiala Jail in the garrison city of Rawalpindi, his lawyers said.
The judge said Qadri had committed terrorism and asked him if he had intentionally killed Taseer.
Qadri claimed his action was not illegal as he had dealt with "an apostate" according to the Quran and Islamic laws, a member of the policeman`s defence team told the media.
There was confusion on whether Qadri had pleaded guilty, with some members of his defence team telling the media that he had "pleaded not guilty".
The judge scheduled the next hearing for February 26, when evidence and witnesses will be presented by the prosecution.
Prosecutors had stayed away from several earlier hearings in Qadri`s case, apparently due to security concerns.
Qadri had surrendered after firing at Taseer and said he had been angered by the politician`s opposition to the blasphemy law and his support for Asia Bibi, a Christian woman sentenced to death last year for allegedly insulting Prophet Muhammad.
Qadri was part of the security detail for Taseer, who was hit by 27 bullets.
The assassination of the liberal politician divided Pakistani society after religious hardliners and even groups of lawyers hailed Qadri as a hero.
The developments also showed how religious extremism had penetrated society, and many analysts blamed this phenomenon on laws and policies introduced by the regime of late military ruler Zia-ul-Haq.
Some persons came to Adiala Jail with Valentine`s Day cards and flowers today to express their support for Qadri.
At earlier court appearances, Qadri was feted and showered with rose petals.