More than a million Christmas lights were switched on in Canberra's CBD last night, officially breaking the Guinness World Record for the largest LED image display.

It took lighting architects, designers, electrical and civil engineers months to plan and build the display in Petrie Plaza, which carried on an annual tradition started by the Richards family of Forrest.

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David Richards and his wife Janean have raised more than $200,000 for SIDS and Kids over the years. ( ABC News )

In previous years, Canberra barrister David Richards broke records decorating his own home, but this year he moved the display to the CBD.

Mr Richards said the light show would raise money for SIDS and Kids ACT, a charity that assists families affected by sudden infant death syndrome in Canberra that was close to his family's heart.

"We had a tragic loss in 2002 and SIDS and Kids Australia and ACT assisted us and assisted our family members and we're just trying to give something back," he said.

Over the years Mr Richards and his wife Janean have raised more than $200,000 for the charity.

'An incredible way to bring the community together'

Mr Richards said this year's display was a mammoth effort.

"As you can imagine the regulatory process for installing a 22 tonne structure with 110 kilometres of electricity on it is a huge process," he said.

"The ACT Government has assisted us, we've got the structure and here we are. We've had about a hundred people that have worked for free."

SIDS and Kids ACT chief executive officer Nathalie Maconachie said the project started construction back in October and it had been amazing to watch it all come together.

"David's energy, drive and passion astound me, and our organisation is truly grateful. What an incredible way to bring the community together at Christmas," she said.

The display will continue until New Years Eve.