The next move will be up to the bill's opponents who have massed in Bangkok streets and staged protests in Phuket and many provinces around the country.
Academics and professionals in Thailand have expressed their opposition to the bill, which comes before the Senate on November 11.
Tourists from sensitive countries including China and Japan are likely to begin cancelling visits to Thailand following today's announcement.
Declining to back away, Khun Yingluck urged senators to support the bill ''for Thailand's future harmony.'' She called on stakeholders ''to forgive each other.''
She said it was the role of MPs to carry out the move to bring harmony to Thailand, where the divide between ''red'' government and ''yellow'' opposition remains strong.
The amnesty grants pardons to many corrupt officials and opens the door to the return of fugitive Prime Minister Thaksin Shinawatra, the present PM's brother, who remains a powerful force despite his absence from Thailand since 2006.
Khun Yingluck, dressed in sombre grey and surrounded by key ministers, told Thais today that she intended to pursue the amnesty.
''It doesn't mean we will forget,'' she said. ''But we have to look to the future, not the past.''
So far the bill appears to have splintered ''red'' supporters, with the issue now broader than the usual political divisions.
The Government pushed through the bill on Halloween night and protests have been springing up around the country ever since.
A protest on Phuket on Sunday drew a large crowd of 5000 from all walks of life. Many of the crowd, like protesters in other provinces, immediately heading for Bangkok where thousands remained on the streets today.
By speaking out today, Khun Yingluck put herself firmly behind the bill. Until now, she has carefully avoided being seen to be too supportive, leaving it to MPs to drive the process forward.
Some observers see thie amnesty as an all-or-nothing bid to return Khun Thaksin to Thailand, where he would quickly resume his powerful position.
However, one New York Times reporter noted today that even traditional Thaksin supporters see that the amnesty is already splintering his support.
Khun Yingluck was due to head to Pattaya this afternoon to comfort Thais and tourists injured in a ferry capsize that killed six people, including two Russians and a man from Hong Kong, two days ago.