"The last 12 months has taken a huge toll on us all, and I offer my sincere condolences to those who have lost loved ones. Today, the anniversary of the first lockdown is an opportunity to reflect on the past year - one of the most difficult in our country's history", Johnson said in his address.
The prime minister noted that everyone played a role in the fight against the pandemic, be it frontline workers, such as doctors and nurses, scientists developing vaccines, or those who simply stayed at home to prevent the spread of the virus.
"It's because of every person in this country that lives have been saved, our NHS [the National Health Service] was protected, and we have started on our cautious road to easing restrictions once and for all", Johnson added.
At the same time, the prime minister warned about a third wave of the pandemic in the country, as it has already prompted some European nations to reimpose new lockdown restrictions.
On what is called a national day of reflection, memorial ceremonies will be held across the country, including a minute's silence at noon. At 20:00 GMT, people will be invited to light candles or lanterns as a sign of respect for the memory of the victims of the pandemic.
The initiative to hold on 23 March a national day of reflection, supported by the UK authorities, was proposed by the Marie Curie charity that helps people with terminal illnesses and their families.
Over the past year, the death toll from the coronavirus in the UK has risen from 364 to 126,172.