Wednesday's release also included Dr Walid Bunni, Fawaz Tello, and lawyer Habib Eissa.
Seif, a former member of the Syrian Parliament, told Aljazeera that his release was a move in the right direction by the authorities and acknowledged it came after international pressure on Syria.
He said: "We all know that the current local, regional and international circumstances necessitate a review of all the policies of the past and re-evaluating them and moving to a new stage.
"Every Syrian citizen must feel that he has a country and that he is required to participate in the building of this country and that he has duties and responsibilities."
The five men were arrested with five others in 2001 after what was dubbed by western press as the "Damascus Spring".
It was a period of liberalisation by Bashar al-Assad, Syria's then new president. Al-Assad introduced a measure of political freedom in Syria after succeeding his late father Hafez al-Assad, but the authorities have since cracked down on dissidents, saying they wanted to change the constitution and endanger the state.
Seif, 54, and Homsi, 45, were jailed on charges of working "to change the constitution through illegal means", an offence punishable by between five years and life in jail.
Homsi started a hunger strike to
push for political reforms
Seif told Aljazeera after he was freed: "We refused any precondition ... We even insisted on deleting a routine sentence, which reads 'I have reformed myself', while signing the request for release.
"We will not 'reform ourselves' because we did nothing wrong. We were endeavouring for the public good.
"Four years and seven months after our arrest, it has become evident that we were right and we would have spared the homeland much, much (trouble) had the authorities acted differently at the time."
Seif told Aljazeera he and the others were freed under a provision in the Syrian law that enabled them to be released after serving three-quarters of their terms, though the release should have occurred earlier.
Damascus has been under heavy western pressure since a UN investigation implicated Syrian intelligence in last year's assassination of Rafiq al-Hariri, a former Lebanese prime minister.
George Bush, the US president, called on Syria last month to release at least nine political prisoners, including the five, after accusing it of denying opposition activists "the fundamental right to freedom of opinion and expression".
Seif, who organised political debates at his home, was summoned on 6 September, 2001 and also accused of inciting inter-religious division, forming a secret society, organising subversive meetings and gatherings aimed at causing disorder, his lawyer said.
Homsi, who had started a hunger strike to push for political reforms, was detained on 9 August, 2001 and accused of aggression aimed at impeding the authorities from carrying out their duties, inciting inter-religious dissent, defamation towards state institutions and resistance towards the authorities, his lawyer said.
"It is necessary to definitively close this file by releasing all political prisoners and closing exceptional courts"
The arrests drew condemnation from human rights groups.
Anwar Bunni, the group's lawyer, and the brother of Walid Bunni, one of the released men, said: "It is necessary to definitively close this file by releasing all political prisoners and closing exceptional courts."
Bunni estimated that 1500 political detainees are still languishing in Syrian jails.