Laguarta, who starts on Oct. 3, will be tasked with managing the company's response as consumer tastes move away from sugary drinks.
Nooyi, 62, is stepping down after 24 years at PepsiCo, where she held a variety of roles, including her most recent 12 years as CEO. Her departure also leaves only one woman of color among Fortune 500 CEOs.
Laguarta will be PepsiCo's sixth CEO in its 53-year history.
"Ramon Laguarta is exactly the right person to help build on @PepsiCo's strong position and success. He has been a critical partner and friend and I am positive that he will take PepsiCo to new and greater heights in the years to come," Nooyi tweeted on Monday.
A 22-year veteran of PepsiCo, Laguarta oversaw global operations, corporate strategy, public policy and government affairs in his role as president.
The Spaniard previously headed the company's Europe Sub-Saharan Africa (ESSA) division - a unit PepsiCo characterized as "one of the most complex business divisions in the company," due to its mix of both developed and emerging markets.
Laguarta, 54, was named president of the company in September last year and was tipped to succeed Nooyi. He also formerly led PepsiCo's Eastern European operations.
"With a deep understanding of PepsiCo's international operations, and a broader understanding of the total company portfolio in his role as president, we believe that Laguarta is well-placed to continue executing on PepsiCo's current strategy," Cowen & Co analysts said.
PepsiCo's shares were up 1.6 percent in morning trading on Monday, touching a seven-month high of $118.21 earlier in the session.
Nooyi is the third female CEO to leave a Fortune 500 company in the last one year after Denise Morrison quit Campbell Soup in May and Irene Rosenfeld stepped down as the head of Oreo-cookie maker Mondelez International Inc in August 2017.
That leaves only 23 female CEOs at Fortune 500 companies, representing less than 5 percent of the total, according to the Fortune magazine.
In her climb to the top, Nooyi had been at the forefront of several deals that reshaped PepsiCo. While she was chief financial officer, PepsiCo bought Quaker Oats and when she was vice president of corporate strategy, it spun off its interest in Pizza Hut, KFC and Taco Bell.
However, it was after becoming CEO in October 2006, that Nooyi cemented PepsiCo's dominance in the global snacks and drinks market - inking 80 tactical deals, including buying its bottling operations and the Naked juice brand
She has also bolstered its portfolio of healthier offerings, which now account for nearly half of its sales, compared with about 38 percent in 2006, better aligning its portfolio with evolving consumer tastes, according to Morningstar analyst Sonia Vora.
More recently, Nooyi focused on reinvigorating sales of its marquee sodas by stepping up marketing efforts to win market share from Coca-Cola.
As CEO for 12 years, she has boosted sales of the Mountain Dew and Gatorade maker to $63.5 billion, up 80 percent from when she started. The company's share price has risen 78 percent in the same period.
She also saw off billionaire activist investor Nelson Peltz's efforts to spin off the company's drinks business from its more successful snacks division by offering his fund, Trian, a board seat in 2015 to make peace. The hedge fund exited its stake in 2016.
Wells Fargo analyst Bonnie Herzog, however, said the change at the top could see PepsiCo considering more strategic options.
"This transition could open a wider door to PEP considering a variety of potential alternatives, including stepped up refranchising or even potentially splitting up the company."
Nooyi will remain chairman of the board until early 2019.
PepsiCo said it has not yet entered into any compensation arrangements with Nooyi or Laguarta with respect to changes in their job roles.
(Reporting by Siddharth Cavale and Uday Sampath Kumar in Bengaluru; Editing by Anil D'Silva, Bernard Orr)
By Siddharth Cavale and Uday Sampath Kumar