It is the first time the bike hire scheme has been available to the 80,000 Londoners living in the Brixton area.
The new cycle docking stations can be found on St John’s Crescent, Ferndale Road and Saltoun Road, in Brixton, and Cranmer Road, Normandy Road, Wynne Road, and Sidney Road in Stockwell.
Lambeth Council said it would continue to campaign for more cycle hire options south of the River Thames.
Santander Cycles can be hired for as little as £2 a day to ride around the city or £90 for a season ticket.
The Mayor of London, Sadiq Khan, said: “It’s great news that our hugely popular Santander Cycles scheme has today expanded to the streets of Brixton.
“I have no doubt that the bright red bikes will quickly become a familiar sight across Brixton, as they help tens of thousands more Londoners and visitors travel easily across the area.
“It’s yet another boost for our record-breaking scheme and for our work to make cycling more accessible, improve London’s air quality and tackle congestion.”
Will Norman, London’s Walking and Cycling Commissioner, said: “After their most successful year ever, I’m so pleased that we can today expand Santander Cycles into Brixton.
“The introduction of our new bikes last year has already proven to be a huge success, I know this expansion in south London is going to allow even more people to enjoy cycling around our capital.”
Cllr Jennifer Brathwaite, Lambeth Cabinet Member for Environment & Housing, said: “I’m delighted that Santander Cycles are finally here in Brixton.
“This is something we’ve been working on for a long time with TfL as we continue to make it as easy as possible to cycle around Lambeth.
“The borough is fast becoming the most cycle-friendly in London and this is another way people can start travelling more ‘actively’, improving health and wellbeing, and contributing to cleaner air – something we’re particularly passionate about.
“We are proud to have a Low Emission Bus Zone in Brixton and Streatham now, helping to reduce pollution around the main roads and Lambeth also provides cycle training, has a great and improving network of safe cycling routes, a free try before you bike scheme and hundreds of cycle hangers to help with bike storage.
“We will continue to campaign for similar cycle hire options further south in the borough so that even more residents can benefit.”