Spaniard Pedro de la Rosa rejoined McLaren as the team's official Formula One test and reserve driver after losing his race seat at Sauber last year.
"Of all the teams I've driven for in Formula One...McLaren is the one that really feels like home," said the 40-year-old, who was dropped by Sauber in September and ended the season as tyre supplier Pirelli's test driver.
"So I'm very excited about returning to the team to help push the development of the MP4-26 (car)," he added in a statement.
McLaren said Britain's Gary Paffett will also retain his role as a test driver, while racing for Mercedes in the German touring car (DTM) championship, but will no longer attend grand prix weekends.
De la Rosa worked previously with McLaren for seven years, including starting nine races for them as a stand-in during the 2005 and 2006 seasons. He also raced for Arrows, Jaguar and Sauber after making his debut in 1999.
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"He rejoins us with even greater experience, and his motivation and attention to detail remain as sharp as ever," said team principal Martin Whitmarsh.
"His recruitment adds considerable strength in depth to our driver lineup.
"With two world champion race drivers in Lewis (Hamilton) and Jenson (Button), and two of the world's most experienced and capable development drivers in Pedro and Gary, we feel we have a quartet of talent that is absolutely second to none."
