Janina Gehlau, 26, from Dusseldorf, died in October 2014 when the lorry turned left at Ludgate Circus, pulling her under its wheels.
A jury at the Old Bailey found him not guilty after an hour's deliberation.
Gehlau's mother said she hoped her daughter's death would make people "think twice before cycling in London".
Vincent Doyle, 45, failed to spot the German postgraduate in the cycle lane, despite overtaking her 200 metres before the junction, where he waited for 23 seconds at a red light.
Had his mirrors been correctly positioned, he would have had her in his sights for three to five seconds before his wheels clipped hers, sending her underneath the vehicle, the court heard.
Mr Doyle said he always made safety checks and had looked in his mirrors "five or six times" before the green light.
He told jurors that he never saw Mrs Gehlau waving her arms or heard her shouting before she fell under the lorry. He felt a "bump" and looked in his mirror to see her head sticking out, he said.
Mr Doyle described how he held her hand and pleaded with her to "hold on".
"I was taking her pulse, chatting to her all the time. I was holding her hand telling her 'Please hang on'. We were chatting away. And then she died. She died just as the ambulance got there."
On how the accident had affected him, he said: "I had a nervous breakdown last year. I was in psychiatric hospital for eight months."
In a statement, her mother Andrea Tasic said: "We are devastated by the verdict and do not feel that we have got justice for Janina.
"I miss her so much. She had a great future ahead of her and it was erased in a moment.
"I told her I thought the roads were too dangerous when I visited her, but she was an experienced cyclist and told me not to worry, she said it would be fine.
"My only hope is that this makes people think twice before cycling in London."
The widower of a German student killed by a lorry in London sobbed as its driver was cleared of causing her death by careless driving.