Mr Khan and his family were met by a huge group of reporters as he arrived at London's City Hall for tonight's declaration of the crucial mayoral race.
In a glimmer of light for Jeremy Corbyn from an otherwise dire set of election results, emerging results at City Hall made it clear there was no route to victory for Mr Goldsmith.
The official declaration was originally due around 6pm but 'discrepancies' in the count pushed the final result back.
As midnight approached there was still no official declaration and suggestions that glitches in the electronic counting system might delay the final result.
LBC's political editor Theo Usherwood tweeted: 'I am hearing the problem with the count is more significant than was first let on.
'The computer which counts the votes has apparently allocated them to the wrong party. We are apparently talking hundreds of votes in each of the 72 parliamentary constituencies.'
A London Elects spokesman said: 'We have to take the time to resolve these issues. We are working towards a declaration at midnight. I apologise.'
But elections expert Michael Thrasher declared the contest was over based on figures already released which showed it was impossible for Mr Goldsmith to catch up on second preferences.
The bitterly contested battle had seen Mr Goldsmith and David Cameron repeatedly raise Mr Khan's ties to extremists.
But the interventions did not sway voters in the capital – and the Prime Minister is now facing a massive Conservative backlash over the tactics.
Mr Corbyn welcomed the victory by tweeting: 'Can't wait to work with you to create a London that is fair for all.'
[. . .]
Mr Khan scored more than a million votes on the first round alone and appeared likely to rack up the largest individual mandate in British electoral history once second preference votes were included.
Steven Norris, a former MP and mayoral candidate, insisted it was 'no use having a dog whistle when everybody can hear it' as he led criticism of Mr Goldsmith's campaign.
Andrew Boff, the Conservative leader on the Greater London assembly, said the strategy had been a mistake and could damage relations with the Muslim community.
Roger Evans, a deputy to Boris Johnson at City Hall, also weighed in, warning that Mr Goldsmith's campaign would leave a 'negative legacy'.
In a remarkable broadside on the Tory mayoral candidate, Mr Boff said his party's tactics could damage relations with the Muslim community.
Roger Evans, a deputy to Mr Johnson, also weighed in, warning that Mr Goldsmith's campaign would leave a 'negative legacy'.
while the Tories go to war over Zac Goldsmith's 'outrageous' and 'divisive' campaign
Sadiq Khan scored more than a million votes on the first round of the result
Data revealed Zac Goldsmith had no route to victory ahead of final scores
Khan won more votes as an individual British politician than anyone ever
As he faces defeat Goldsmith has come under fire from his own side
Andrew Boff, Tory leader on the London Assembly, and former deputy mayor Roger Evans have slammed Goldsmith's negative tactics
Official announcement delayed by glitches in electronic counting system
By JAMES TAPSFIELD, POLITICAL EDITOR FOR MAILONLINE and TIM SCULTHORPE, MAILONLINE DEPUTY POLITICAL EDITOR and MARTIN ROBINSON, UK CHIEF REPORTER FOR MAILONLINE
PUBLISHED: 03:58 EST, 6 May 2016 | UPDATED: 18:00 EST, 6 May 2016