Ingram is replacing Cara Parish, who is moving to New York.
Ingram has spent the past two years at Clarity PR running campaigns for tech start-ups including Firefly, Signal, Big Health, Sandbox & Co and WorkAngel. She has previously worked at The Engine Group.
In her new role she will be responsible for running Cult's PR functions including its quarterly events, called #CultHosts.
In a statement, Cult LDN founders Cat Turner and Bridey-Rae Lipscombe said: "Lauren brings with her a wealth of industry experience and a broad network of opportunities for Cult as a business. Having seen unprecedented growth in 2015, we are keen to invest more than ever into a sound marketing strategy.
"Lauren's remit will include continuing to run our quarterly series of events – #CultHosts – along with our breakfast briefings and trend reports."
Ingram will work alongside marketing manager Natalie Bell.
Cult was launched in 2012 and now has 32 staff in London. The agency has an all-female senior management team. Its clients include Barbour International, Katy Perry perfume, Sally Hansen, Rituals and Pan Macmillan.