"I was here to offer my party's thanks to Sonia Gandhi for supporting us," she told reporters here.
The DMK chief M Karunanidhi's daughter was accompanied by senior party leader and former union minister T R Baalu during her meeting with Gandhi.
She was re-elected to Rajya Sabha with Congress support from Tamil Nadu after a contest with actor Vijayakanth's DMDK candidate A R Elangovan on Thursday.
45-year-old Kanimozhi, an accused in the 2G scam, sailed through the contest for a second term with 31 votes after five Congress' MLAs voted in her favour along with two votes each from two smaller parties - Puthiya Thamizhagam and Manithaneya Munnetrak Katchi.
Congress' decision to support DMK came as a surprise against the backdrop of the bitter separation between the two parties after nine years of friendship in the UPA coalition earlier this year over the issue of alleged human rights' violations of Tamils in Sri Lanka.