Nicholas Foy, 38, carried out the unprovoked knife attack on 49-year-old father-of-two Laurent Volpe as he was walking to shops in Eltham to buy dinner for his family.
Mr Volpe, with his wife and two children, had spent the day on August 11 last year sightseeing at Tower Bridge and Greenwich Observatory.
He was heading to the CoOp near to his rented accommodation when he was attacked, managing to stagger to a shop to get help after being knifed in the stomach. However he died in hospital three days later.
The Old Bailey heard Foy threatened to stab others at the scene and had to be Tasered several times before he was finally brought under control.
He claimed at trial that he had not intended to cause really serious harm because he was so drunk at the time of the stabbing. But a jury this morning found him guilty of murder by a majority of 11-1.
Judge Sarah Munro QC adjourned sentencing until Friday when Foy will be jailed for life.
In an impact statement, Mr Volpe’s wife, Cecile Chapuis, told the court she has a “tremendous sense of loss and suffering since the death of Laurent.”
Describing him as “smiling, kind, passionate, and full of life”, she said: “I do not have a partner to share daily events of life, joy and sadness.”
She added that her children now feel there is “a part of you that is no longer there – an empty space”.
Prosecutor Oliver Glasgow QC told the trial Foy was “fuelled with a deadly combination of alcohol and cocaine” when he carried out the “entirely unprovoked” stabbing.
Foy smelled of alcohol when he was picked up that morning to go to work as a warehouse delivery worker. He was sent home rather than going on his usual rounds, and was next seen at around 6.45pm, wearing only a pair of pink shorts and trying to gouge at his foot with a kitchen knife.
“The defendant ran towards Mr Volpe with the kitchen knife in his hand and stabbed him once in the stomach”, said Mr Glasgow, describing the attack.
“Nothing was said by either him or Laurent Volpe and the attack was completely unprovoked.”
Foy grabbed a dustbin lid to fend people off afterwards, and tried to escape back to his home through gardens before he was detained.
He denied murder but was convicted by the jury.