Tribute bands will be performing in the city, beginning with early performances for workers and culminating in a concert at Liverpool Arena.
People in the city are being urged to wear "mop-top" wigs, with the profits to go to charity, including Alder Hey Imagine Appeal and Liverpool Unites.
The date was chosen as the anniversary of the day the Beatles returned to Liverpool after conquering the US.
Performers at the tribute concert include the Backbeat Beatles, Gerry Marsden, Billy Butler, Tony Crane and Billy Kinsley from Merseybeats and Mike Pender from the Searchers.
Other events include a performance by the Beatelles, an all-girl Beatles tribute band, on the roof of BBC Radio Merseyside and a themed parade past places including Strawberry Fields.
Merseytravel staff, including those on the city's ferry across the Mersey are also being encouraged to wear the wigs.
The day's first ferry passengers, until 0900 BST, are being serenaded by tribute bands.
The plans for the regular day were revealed by Liverpool actor Ricky Tomlinson at Alder Hey at a launch day in April.
Copyright Speakers Corner 2016