London Ambulance Service (LAS) and St John's Ambulance treated 295 people around the Mayor's New Year's fireworks event on Sunday night (December 31).
A large number of those treated in Westminster and on the Southbank were said to suffer "alcohol-related illnesses".
LAS and St John Ambulance helped NYE revellers to "sober up" or treated them for minor injuries before they were discharged.
LAS said New Year's Eve is its busiest night of the year and on Sunday it took up to 400 calls an hour when it normally takes 250.
New Year's day news
Ambulance staff were busiest from 2am and 3am on Monday (January 1) when LAS received 402 calls.
St John's Ambulance and LAS staff worked on foot in teams carrying vital medical equipment around Waterloo and Lambeth Bridge to the Victoria Embankment and Trafalgar Square and Covent Garden.
LAS director of operations, Pauline Cranmer, said: "It has been a busy night for us and we worked closely with St John's Ambulance at nine treatment centres to ensure people out celebrating received the most appropriate medical care as quickly as possible.
"It also meant we avoided taking them to busy A and E departments."
She added: "We expect to be busy throughout New Year's Day as many Londoners will feel unwell after a heavy night."
LAS encourages worse for wear revellers to use other health care services on New Year's day, such as walk-in centres or to call NHS 111 for health advice, so ambulance staff are free to respond to people in serious or life-threatening conditions.
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