The force said it wanted to reassure the 300,000 racegoers expected to descend on the Berkshire town ahead of the five-day event's Tuesday start.
"Those attending should go about their day as normal," a force spokesman said.
Armed patrols were deployed at Royal Ascot, which the Queen will attend, for the first time in 2016.
In a statement, Thames Valley Police said there would be more armed response vehicles, uniformed and non-uniformed police officers, vehicle checks and baggage searches this year.
"For all involved, this year's event will feel a little different in light of recent, tragic national events," added Supt Olly Wright.
A Royal Ascot spokesman said access to the racecourse will take longer as a result of the additional security.
"We ask that you do not bring unnecessary bags or luggage into the racecourse," the spokesman said.
"The safety of all racegoers is paramount and racegoers can be assured that the racecourse works extremely closely at all times with the police, the security services and specialist advisers," the spokesman added.
Royal Ascot will feature more armed officers and security checks following the London and Manchester terror attacks, police have said.