The six-figure patient list landmark was reached after GP at Hand's patient list grew by 1,509 patients in the month to 1 August, and comes just months after it became England's largest GP service for the first time.
The service, run by private provider Babylon under a subcontracting arrangement with what was a small GP practice in west London, now has 101,267 patients according to figures published by NHS Digital - more than 20 times the total registered with its host practice in November 2017.
GP at Hand has been accused of 'cherry-picking' patients - a charge it denies - because its patient list is different from the population of England as a whole, and substantially skewed towards younger, and to an extent male patients.
A total of 46% of its patient list are aged between 20 and 29 years old - compared with 13% of the population as a whole, while 85% of GP at Hand patients are aged between 20 and 39 - compared with just 28% nationally.
Meanwhile, the population of England as a whole is split evenly between male and female - while the GP at Hand population is 55% male and 45% female.
In the month to 1 August, the GP at Hand patient list grew by 1.5% - roughly 15 times the rate of increase of the population registered with GP practices nationally.
Patients registered with the service have risen rapidly since November 2017. At that time, its host practice, the Lillie Road Medical Centre in Fulham, had less than 5,000 patients - but under the deal with Babylon has used out-of-area patient registration rules to sign up patients across a wide geographical area.
The service promises rapid access to predominantly video consultations, but patients can also see a GP at one of seven physical locations in London and one in Birmingham. GP at Hand has said it hopes to open a further service in Manchester. Currently, more than 90% of its patients are based in London, according to Babylon.
Commenting on the rise of GP at Hand last year, BMA GP committee chair Dr Richard Vautrey said: 'The BMA has always made clear its concerns about the impact that this model has on the stability of general practice.
'When largely younger and healthier patients deregister from their original practice, not only do they lose the continuity of care provided by their local GPs and teams , but it also reduces the much-needed resources available to these practices so they can care for their sickest patients.'
A Babylon spokesperson said: 'We’re honoured that over 100,000 patients have chosen Babylon GP at Hand as their primary care provider. This growth is testament to the benefits of a digital-first service which gives patients more choice and increased accessibility through 24/7/365 digital appointments, while also allowing clinicians to focus on the areas they are needed most.
'In the recent independent GP patient survey, we were proud our GP at Hand patients gave our GP practice, including our doctors, appointments and overall process, great reviews across the board. We scored higher than the national and local average in 14 out of the 18 areas.
'The digital-first nature of the service means it is especially attractive to patients between 18-55 years of age who typically use technology more. This demographic is also often time poor because of work or family commitments so value a 24/7/365 service that lets them access care for themselves and their families at home. However, Babylon is open to all people.'