On Friday, India's parliament stripped Mr Gandhi of his MP status a day after he was sentenced to two years in prison in a defamation case.
He was convicted by the court for 2019 comments about PM Narendra Modi's surname at an election rally.
The governing BJP says his expulsion conformed with parliamentary rules.
A 2013 Supreme Court order says that a lawmaker convicted in a crime and sentenced to two or more years in jail stands disqualified from the parliament with immediate effect.
Speaking at a news briefing on Saturday, Mr Gandhi said: "It makes me no difference if I'm disqualified... Disqualify me for life.... I will keep going, I will not stop."
Although India's opposition parties don't always agree on political issues, many of them have supported Mr Gandhi over his disqualification. On Friday, 14 parties approached the Supreme Court, alleging that the federal government was misusing investigative agencies to target BJP's opponents.
Congress president Mallikarjun Kharge alleged that the action against Mr Gandhi was a consequence of his demand for a parliamentary investigation to probe allegations against the Adani Group.
The huge conglomerate was accused of decades of "brazen" stock manipulation and accounting fraud by US-based short-seller Hindenburg Research earlier this year. The Adani Group has denied allegations of financial fraud.
"My job as I see it is to defend the democratic nature of this country," Mr Gandhi said after his disqualification.