The building, which has stood for 1,000 years, closed in May last year in the wake of the coronavirus pandemic.
It was one of six historical sites run by Historic Royal Palaces that wer forced to close.
The other sites included Hampton Court, which reopens on May 20, the Banqueting Hall, whic is yet to reopen and Hillsborough Castle, which is closed until further notice.
Kew Palace was also on the list but reopened today.
The Tower of London is now open from 10am to 8pm as well as during the half-term holidays and tickets start from £14.90.
The reopening came after the UK entered the next phase of its roadmap out of lockdown with restaurants and pubs now allowed to serve customers indoors.
People can also meet outdoors in groups of up to 30 while indoor entertainment including cinemas, bowling alleys, museums, and children’s play areas can also resume.