The government has described it as a "pivotal moment" in the fight against coronavirus.
Some 530,000 doses will available, initially at six hospital trusts - Oxford, Sussex, Lancashire, Warwickshire, and two in London.
The bulk of the supplies will then be sent to more than 700 GP-led services and care homes.
The government hopes it will deliver tens of millions of doses within months, with the reported goal of administering two million per week.
Health Secretary Matt Hancock said: "This is a pivotal moment in our fight against this awful virus and I hope it provides renewed hope to everybody that the end of this pandemic is in sight."
He urged everyone to continue to follow the coronavirus restrictions while the vaccination programme is under way to “keep cases down and protect our loved ones”.
So far, around one million people in the UK have received the other approved vaccine, which is produced by Pfizer and BioNTech.
The Oxford-AstraZeneca vaccine, however, is cheaper and easier to store and transport.
Jabs will be delivered at some 730 vaccination sites already established across the UK, with others opening this week to take the total to more than 1,000, according to the Department of Health and Social Care (DHSC).
The vaccine will be administered at a small number of hospitals in England for the first few days, including at Oxford University Hospitals NHS Foundation Trust, where it was developed.
The spread of the new more transmissible variant of Covid-19 has forced the government to prioritise giving the first dose of the vaccine to as many people as possible, rather than concentrating on giving a smaller group of people the full two doses first.
But challenges remain in rolling out the vaccination and reaching the government's target of vaccinations per week.
The Daily Telegraph quoted an unnamed health source as saying that people should not expect huge numbers overnight.
They added: "We have never said we will do two million jabs a week. We have to manage expectations. You cannot vaccinate two million people a week from nothing. People will be underwhelmed by the figures if expectation is set too high."
The UK has secured 100 million doses of the Oxford/AstraZeneca vaccine as part of its contract, enough for most of the population.
It comes as another 54,990 people tested positive for COVID-19 in the UK - the sixth day in a row that new daily cases have exceeded 50,000.
A further 454 people have died with coronavirus, government figures show.
It takes the total number of people who have died within 28 days of a positive coronavirus test in the UK to 75,024.
GPs and local vaccination services have been asked to ensure every care home resident in their local area is vaccinated by the end of January, according to DHSC.