Laguarta, Nooyi successor, has held a number of executive and general management roles in his 22 years at PepsiCo.
In a series of posts on Twitter, the businesswoman referred to her upbringing in India and said she "never imagined" she'd have the opportunity to lead a company like PepsiCo. Sixty-two-year-old Nooyi, who has been a part of the company for 24 years, will continue as the chairman of the board till early next year.
Nooyi led Pepsi to become one of the most successful food and beverage companies in the world. "Leading PepsiCo has truly been the honour of my lifetime, and I'm incredibly proud of all we have done over the past 12 years to advance the interests not only of shareholders, but all our stakeholders in the communities we serve", she said in a statement.
"Today is a day of mixed emotions for me".
In a statement, Ian Cook, presiding director of PepsiCo's Board of Directors, lauded Nooyi for 'leading the way on corporate sustainability and responsibility, and embedding a sense of objective in everything the company does'.
"Ramon Laguarta's unanimous appointment follows a systematic and thorough succession process by the Board of Directors".
Laguarta has previously served in leadership positions in PepsiCo's European and sub-Saharan Africa divisions.
He now serves as president, overseeing global operations, corporate strategy, public policy and government affairs.
He was elevated to president in September of past year and was widely expected to succeed Nooyi, though at the time of his appointment Nooyi said she would remain CEO "for the foreseeable future".
With Nooyi's departure, the rest of PepsiCo's senior leadership team will remain unchanged, the company said.