Mrs Dewani, 28, died after the car she was travelling in with her husband, Shrien, 31, was hijacked in Cape Town.
The vigils were held on 13 November in Bristol, London, Cape Town and also Sweden where she was born.
South African authorities have applied to have Mr Dewani extradited over claims he was involved in her murder. He denies the charges.
Taxi driver Zola Tongo from Bothasig, Cape Town, has been jailed for 18 years for murder, kidnapping, robbery with aggravating circumstances and perverting the course of justice after agreeing a plea bargain.
Mr Dewani, from Bristol, faces charges of murder, conspiracy to commit murder, robbery with aggravating circumstances and obstructing the administration of justice.
Mr Dewani's extradition was backed by Home Secretary Theresa May after a judge approved the move in August.
An appeal has been lodged with the High Court.
Mrs Dewani's uncle, Manoj Panchmatia, who helped organise the vigils, said it had been "a very difficult year for the family".
"We are all looking for some form of closure," he added.
Mr Panchmatia said the idea had come from users of Facebook who wanted to do "something special".
He said the family had received hundreds of emails from people saying they planned to light a candle.
The vigils, including one in Harrow, north London, where Mrs Dewani lived with relatives before getting married, were scheduled for 17:30 GMT.
Two other men, Mziwamadoda Qwabe, 25, and Xolile Mngeni, 23, are also charged with murder, as well as kidnapping and robbery with aggravating circumstances and will go on trial at the Western Cape High Court next year.
Mrs Dewani was shot after a cab the couple were travelling in was hijacked in the Gugulethu township.
Mr Dewani was released unharmed but Mrs Dewani's body was later found in the abandoned car.

Abendanon has won the European Player of the Year award, the third time a French-based English player has won it.
Yet since the 2011 Rugby World Cup, an RFU rule has said only those involved in domestic rugby can play for England.
"Having that rule in place restricts players from playing at the top level," said 28-year-old Abendanon.
"You're playing with the best players in the world and coming here has made me a better player and better person.
"I know exactly why the RFU has that policy in place and I don't expect it to change - but I have changed my mind on it since moving out here."
Abendanon played two matches for England in 2007 but last summer he moved from Bath to Clermont, scoring a fine solo try in the 24-18 loss to Toulon. in the final of the European Rugby Champions Cup.
Toulon's Steffon Armitage and Jonny Wilkinson, now retired, won the European Player of the Year award, in 2014 and 2013 respectively.
After winning the award, Abendanon told BBC Radio 5 live he "would encourage more people to move" to France.
Abendanon has said "it would be a dream come true" to represent England in the 2015 World Cup, but England head coach Stuart Lancaster has only picked domestic-based players.
"I played for 10 years in England and came out to France because I thought my international career was over," added Abendanon. "I'm sure Steffon felt the same.
"Playing in France has rejuvenated our games and whether we get rewarded for that is up to Stuart."
Listen to Abendanon speak to BBC Radio 5 live
Candlelit vigils have been held a year on from the shooting of Anni Dewani during her honeymoon in South Africa.
[NEXT_CONCEPT]
Clermont full-back Nick Abendanon says the Rugby Football Union should allow players working for clubs outside England to represent the national team.