The 40-year-old Australia international was a free agent having been released by Fulham this summer, and will now serve as back-up to first-choice goalkeeper Petr Cech
Schwarzer has signed a one-year contract at Stamford Bridge, and is expected to act as back-up to first-choice goalkeeper Petr Cech.
Jose Mourinho had been the in the market for a goalkeeper following the departures of Ross Turnbull and Hilario, and the announcement Thibaut Courtois will spend another season on loan with Atletico Madrid.
Reports had linked the Blues with a £7 million move for Norwich No.1 John Ruddy, but they have instead chosen Schwarzer, 40, who was released by Fulham following the arrival of Maarten Stekelenburg from Roma.
"It's a phenomenal club," he told the club's official website. "It's one of the biggest and best clubs in the world, and it's an honour to sign for Chelsea. I didn't take much convincing to come here."