The world's longest ocean race - at 40,000 nautical miles - features 700 participants over its eight stages.
The first leg, which launched at St Katharine Docks, will see teams travel 6,000 miles to Brazil's Rio De Janeiro.
On each of the 70ft yachts, only the skipper is professional. The other crew members are all amateurs.
Around 40% of participants had never sailed when they signed up, organisers say.
Boats set off at 14:15 BST from St Katharine Docks and passed under Tower Bridge at 15:30 to the upper pool before beginning the parade along the Thames.
Racing will start off Southend at 12:30 BST on Monday.
Teachers, doctors, IT workers, students and an Ultimate Fighting Championship fighter are all among those taking part.
The youngest participant is 18 and the oldest is 74.
More than half of those taking part - 441 people - are from Britain.
Some crew members will be on board the yachts for the whole course of the journey, while others will compete only in certain stages.
After travelling to Brazil, the yachts will go on to South Africa, then to Albany in Western Australia.
From there, participants will sail to Queensland, and on to Vietnam and China.
They will continue to Seattle and from there to New York via Panama.
The final leg will see the yachts travel from New York back to London, where they are due at the end of July next year.
The Clipper Round The World Yacht Race, which sees 12 teams spend a year travelling the globe, has set off from London with a parade along the Thames.