Nadine Clarke, of Midhurst Gardens, was jailed for 28 months after admitting three charges of supplying class A drugs.
She was also served with an Anti-Social Behaviour Order (ASBO) banning her from the Soho area for seven years.
Miss Clarke, 28, is one of 32 people sentenced for supplying class A and B drugs as part of Operation Rense, targetting street dealers in central London.
A further eight people are to be sentenced in September and October.
Westminster Police Commander, Alison Newcomb, said: "This is a sustained campaign by the MPS, led by Westminster officers, to knock out the criminal markets in Soho and the West End."
