The 36 spacecraft went up on an Indian LVM3 rocket from the Sriharikota spaceport in Andhra Pradesh. Their deployment 450km above the planet takes OneWeb's total in-orbit constellation to 618.
It's less than three years ago that the UK government took the decision to buy OneWeb out of bankruptcy. At the time, it was seen as controversial; arguments raged about whether it was a sound use of taxpayer money.
But since the purchase, OneWeb has managed to attract significant additional investment, and is even now planning a next generation of satellites.
It will take some months for the Sunday's batch of satellites to be tested and to get into the right part of the sky (at an altitude of 1,200km), but when they are in position OneWeb will have the facility to deliver a global communications service.
Only one other organisation in the world is flying more satellites in space today - and that's OneWeb's chief competitor: the Starlink system operated by Elon Musk.
Unlike the US entrepreneur's network, OneWeb is not selling broadband connections direct to the individual user. Its clients, principally, are the telecoms companies that provide this internet service. They might also be employing the connectivity to supplement, or expand, the infrastructure in their mobile phone networks.
The OneWeb system will require the necessary ground infrastructure to command and control all the satellites and link them to the internet, but this too should be fully up and running come the end of 2023.
The satellite enterprise has been a decade in gestation. Projected as a $6bn project, it ran into money woes in early 2020 and sought the protection of US bankruptcy laws until a buyer could be found. At the time, it had lofted just 74 satellites.
The company was restored to operations thanks to a joint purchase from the UK government and the Indian conglomerate Bharti Global, who put in half a billion dollars each.
With its debts wiped out, OneWeb then moved quickly to build out the network and secure wider investment. It's currently working through a merger plan with Paris-based Eutelsat, best known for distributing thousands of TV channels around the world.
UK Secretary of State for Science, Innovation and Technology, Michelle Donelan, said the completion of the low-Earth orbit constellation is hugely significant both for OneWeb and the UK's wider sector.
Safety is paramount. The region in the sky where OneWeb spacecraft are moving - from 450km in altitude up to 1,200km - is becoming ever more congested, and the CAA wants assurance that the constellation is being flown in a responsible manner.
Much of the operation necessarily has to be automated, and the command and control software has had to scale rapidly over the past three years.
Sunday's launch took the number of satellites in space from 582 to 618. In May, another 15 will go up to act as in-orbit spares. These will be joined by a demonstration spacecraft that will trial future technologies.
OneWeb plans to expand its network in the coming years to include bigger, more powerful spacecraft. But contrary to earlier suggestions, the constellation will probably now be kept under 1,000 individual satellites.
The next generation will, though, provide ancillary services, such as signals that allow users to fix their position on the surface of the Earth or know the precise time (a service akin to those currently provided by satellite-navigation systems like GPS and Galileo).
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