Freeview HD consists of the BBC HD channel, Channel 4 HD and ITV1 HD channels, and is already available to 4.5 million homes.
Speaking at Channel 4 this morning, Ilse Howling, managing director of Freeview, hailed the arrival of Freeview HD as "our most important day since Freeview launched".
She said: "We are not pretending to be the first HD product on the market. Other HD products are available but, unlike them, as ever with Freeview, we are for everyone and with great free HD programming."
Eight different TV ads have been created by 18 Feet & Rising for Freeview's HD launch, and will run from this Saturday (3 April) until the end of the World Cup.
The ads will include Freeview's new strapline "It feels good to Freeview" and feature scenes from well-known TV programmes combined with dramatic backdrops from other shows.
Consumers wanting to receive Freeview HD can either buy a Freeview HD enabled TV or purchase either a Freeview+ HD set top box or a Freeview HD box to use with any HD ready TV.
Howling said by the time the Fifa World Cup starts this summer, 50% of UK homes will have access to Freeview HD, and this will rise to 60% by the end of the year.
The goal is to have Freview HD available to the majority of UK homes (90%) by the London 2012 Olympic Games.
Freeview is owned by its four shareholders the BBC, BSkyB, Channel 4, ITV and Arqiva.