The aircraft carrier, which was formally decommissioned in 2011, is being taken to Turkey where it will be dismantled by ship recycling firm Leyal.
People lined the harbour walls at Portsmouth, Hampshire, to catch a final glimpse of the warship as it left its home base.
A flotilla of small boats sailed with the Ark Royal as it was pulled by tug boats from the harbour. The tugs sounded their horns which echoed off the harbour walls as the crowds, some waving flags, stood in silence as the huge ship sailed past.
Hundreds gathered to say farewell to HMS Ark Royal as she began her final voyage to the scrap yard from Portsmouth this afternoon.
Among those who turned out was former crew member John Mayer. The 47-year-old former stores assistant from Fareham said: "It's a very emotional day, it's great to see so many people.
"People in Portsmouth always turn up to these things, it shows how much pride people have in her."
He added: "I was one of the first people to serve on board the Ark Royal after she was built. I was 17/18 at the time and it was quite emotional then. She was a fantastic, iconic ship."
On the decision to scrap it, he added: "I thought it was awful, I think she should have been turned into a museum, it would have been fantastic."
Local resident Barrie Anderson, 70, said: "It's a very sad day."
The 22,000 tonne carrier was sold as part of a £2.9 million deal following the 2010 strategic defence review which led to the ship facing the axe five years early and the Harrier jets being sold for spares to the USA.
The decision to scrap the Ark Royal has left the UK without a fully-functioning aircraft carrier for a total of nearly 10 years until the next generation of carriers come into service.
A Royal Navy spokesman said: "Ark Royal, like her sister ships, served this country with great distinction.
"Retiring her five years earlier than planned was a difficult decision but it was the right one that, combined with her sale, has saved over a hundred million pounds.
"A decommissioning ceremony was held in March 2011 to pay tribute to her 31 years' service with the Royal Navy."
Alternative plans for the Ark Royal, including turning it into a diving wreck, a floating casino off Hong Kong, a heliport for London and a nightclub and school in China were rejected by the Ministry of Defence as "not feasible or appropriate".
The Ark Royal was named by the Queen Mother and entered service in 1981.
It served in the Bosnian war and also sailed to the Persian Gulf for the invasion of Iraq in 2003 and was given a hero's welcome when it returned to Portsmouth.
Source: telegraph. 20 May 2013