The top court rejected the two appeals against the Madras High Court order of 22 March upholding the nomination of the three legislators.
A bench of justices A K Sikri, Ashok Bhushan and SA Abdul Nazeer said, "We uphold the impugned judgment of the Madras High Court".
The High Court had upheld the nomination of BJP members V Saminathan, K G Shankar and S Selvaganapathy to the Assembly by the Centre and their swearing-in by Lt Governor Kiran Bedi on July 4 last year.
The Congress government had opposed their nomination.
The HC had also held as invalid the Speaker's order cancelling the nominations of the MLAs.