A disappointed Zac Goldsmith delivered his concession speech and said triggering the Richmond Park by-election was "not a political calculation".
Mr Goldsmith's majority was slashed by Liberal Democrat candidate Sarah Olney who unseated him with just 1,872 votes in a nail-bitingly close election result.
In his concession speech delivered after the results were announced, ex-Tory MP Zac Goldsmith - who was running as an independent - said he wished Ms Olney well in her new job.
He said: "This by-election that we have just had was not a political calculation.
Richmond Park by-election 2016 - In pictures
"It was a promise that I made that I kept.
"It's been a huge privilege to serve this community and I will miss doing it."
He added: "I love this community."
The former London mayoral candidate said he was extremely grateful to everyone who supported him and to his family, who he expects to now see more of.
Mr Goldsmith quit his seat in October over his former party’s decision to opt for a third runway at Heathrow.
He had promised constituents he would resign if the government opted for the controversial plan.
