Sangma, accompanied by his daughter and Union Minister of State for Rural Development Agatha, met Gandhi at her 10 Janpath residence on Monday evening, sources said.
The meeting, which lasted for about 20 minutes, was described to be cordial.
Sangma met the Congress chief to invite her and her family for the wedding of his son Conrad, who is Leader of the Opposition in Meghalaya.
Sonia also told the father-daughter duo that she was impressed with the Agatha's first tenure as MP and her taking oath in Hindi, sources said.
The NCP general secretary was expelled from the Congress on May 20, 1999, along with Sharad Pawar and Tariq Anwar for raising the banner of revolt against Gandhi over her foreign origin issue.