After a day-long GST council meeting with state finance minister in Guwahati, Mr Jaitley said that only 50 items will remain in the highest tax slab of 28 per cent, with 178 others moved to the 18 per cent bracket from November 15.
Prime Minister Narendra Modi called the decisions "people-friendly and people-centric".
Crediting his party the Congress for pushing for GST Rate cut, Mr Chidambaram said "Congress is vindicated. I am vindicated. The merit of capping GST at 18% is now recognised."
The new GST rate changes come amid allegations that the government's GST roll-out and last year's notes ban have caused economic disruption.
Taking a jibe at the Modi government, Mr Chidambaram said in a tweet the government has "learned its lesson" albeit late. "4 months and 10 days is the time taken for commonsense to germinate, flower and ripen into a fruit."
Congress vice president Rahul Gandhi has been calling the government's blanket 28 per cent GST rate "Gabbar Singh Tax", after an iconic villain from Hindi cinema. "We will not allow BJP to impose a Gabbar Singh Tax on India. They cannot break the back of the small and medium businesses, crush the informal sector and destroy millions of jobs," Congress vice president Rahul Gandhi had tweeted before the GST council meet.