Acute inpatient appointment cancellations now amount to 33,000 in the capital, since the strikes began in December 2022.
An extra 304,000 acute outpatient appointments have also been cancelled due to the continued strikes over the past year.
In the last strike alone, taking place from December 20 to December 23, over 25,000 appointments in London were cancelled and a total of 4,501 staff were not at work across the capital.
Chris Streather, Regional Medical Director for NHS London, said: “We are fast approaching 340,000 appointments rescheduled over more than a year due to strikes.
“We’re continuing to see a massive cumulative impact on NHS services and our hard-working staff as they maintain safe patient services while tackling a record backlog.”
The strike – the longest in NHS history – is part of an ongoing pay dispute with the government, compounded by the usual surge in demand during the winter season.
Starting from January 3, and lasting until January 9, the disruption means only two weekdays have remained unaffected by industrial action or holidays in the NHS for the past three weeks.
Junior doctors make up about half of the NHS workforce, and the predicted effects of their strikes is disruption on a grand scale.
Emergency care remains top priority throughout the strikes and all emergency services will operate as usual.
Mr Streather said: “This time of year is always very busy for the NHS and six days is the longest time that doctors have gone on strike – but we’ve been planning extensively to ensure that people can still access care when they need it.
“It’s important that the public continue to use 999 and A&E in life-threatening emergencies.”
He added: “For everything else people should contact NHS 111 online, as well using local services like GPs and pharmacies for advice and care.
“If you haven’t been contacted or informed that your planned appointment has been postponed, please attend as normal.”