About 2,000 people attended the National Police Memorial Day ceremony, led by Prince Charles.
The family of Constable Fiona Bone, who was killed by Dale Cregan in 2011, attended the service.
The Prince of Wales said the "security challenges of today" emphasised the importance of the police.
Metropolitan Police commissioner Sir Bernard Hogan-Howe and home secretary Amber Rudd were also in attendance.
Police officers who were specially remembered during the service included PC Dave Phillips, who died in October 2015.
The father-of-two was killed when trying to stop a stolen pick-up truck in Wallasey, Merseyside, while crouched on the kerb with a tyre-puncturing stinger.
The truck, driven by Clayton Williams, swerved straight for the police officer and killed him on impact.
The then 19-year-old drug addict was found guilty of manslaughter and sentenced to 20 years in a young offenders institute, as well as being banned from driving for life.
Mr Phillip's eight-year-old daughter Abigail took part in the service by lighting a candle to remember the 34-year-old officer.
Members of the force in Wales, Scotland and Northern Ireland also lit candles during the ceremony.
Prince Charles, who is a patron of the National Police Memorial Day charity, wrote in the order of service: "For many of us, the security challenges of today further underscore the importance of the Police and their ongoing commitment to protecting us all, despite the inevitable risks that they face on a daily basis."
Founder of the charity Joe Holness said: "National Police Memorial Day unites the country in national recognition of officers who have given us their all. It is a significant day of remembrance to ensure our fallen officers must not, and will not, be forgotten."
Police officers who "paid the ultimate sacrifice" by dying in the line of duty have been commemorated at a service at St Paul's Cathedral in London.