Trierweiler "is going to Mumbai," said the aide, adding that the two-day trip was organised by relief organisation Action Against Hunger.
The aid group had invited Trierweiler in her official capacity, but following revelations of Hollande's affair with 41-year-old French actress Julie Gayet, it is unclear if she is travelling as first lady.
Trierweiler remains holed up in a presidential residence in Versailles outside Paris after leaving hospital last Saturday where she was treated for a bout of "tiredness" brought on by the press reports.
But Trierweiler, in a furious reaction soon after, said Giffard was speaking without her permission and added that she was no longer her lawyer.
Hollande had promised in a mid-January news conference that he would publicly define what relationship he and Trierweiler are in before going on a February 11 state visit to Washington.
The 59-year-old leader has so far made no official comment on whether France still has a first lady.