Streatham and Clapham High School was transformed into a conference centre to welcome Robert Winston and the Duke of York.
The private school, in Abbotswood Road, held an event in aid of Ada Lovelace day - an international celebration of the achievements of women in science, technology, engineering and maths.
The conference on Tuesday, October 14, featured coding sessions, talks and workshops run by digital experts. The girls learned to make a website in under an hour, write a game for the web and how to make a computer.
Prince Andrew discussed his digital initiative, iDEA, which aims to support 1m 14 to 25-year-olds to develop their digital skills and ideas.
Lord Winston, a professor and TV scientist, opened the conference with a talk about his pioneering work in IVF and the need for a sound scientific knowledge in all areas of life.
Emma Mulqueeny of Rewired State group, one of the top 10 women in technology, closed the conference with a speech encouraging girls to appreciate the role the digital world will play in their lives and careers, and how important it is women help shape that world.
Dr Millan Sachania, headteacher of Streatham and Clapham High School, said: "This event imparted a sense of adventure, excitement and common purpose that is not often replicated in such conferences. I consider our Ada Lovelace Day a landmark in the broader quest to engage more women with the world of computing and digital creativity."
Ada Lovelace was the daughter of Lord Byron and credited as the first computer programmer when in the 1840s she developed the original algorithm intended to be carried out by a machine.