Conservative politician Craig Mackinlay has been cleared of falsifying election expenses.
The MP for South Thanet had denied making false declarations during his 2015 campaign, when he beat then-UKIP leader Nigel Farage to the seat.
Mr Mackinlay, 52, had been accused of failing to declare more than £60,000 spent on staffing, hotels and adverts.
Jurors at Southwark Crown Court deliberated for more than 53 hours before reaching a verdict.
Party activist Marion Little, 63, from Ware, Hertfordshire, who was tried alongside Mr Mackinlay, was found guilty of two counts of encouraging or assisting an offence.
She was cleared on a further count of the same charge.
Mr Mackinlay responded to the verdict on Twitter, simply writing #notguilty.
Little is due to be sentenced later.
The judge said he was not considering an “immediate custodial sentence” due to the “wholly exceptional” circumstances faced by Little, whose husband is terminally ill.
‘Fear of Farage’
Prosecutor Michelle Nelson told jurors South Thanet would usually have been seen as a safe seat, but Mr Farage’s run as UKIP candidate had been regarded as the chance to “knock him out” of politics.
Mr Mackinlay told the court the Conservative Party HQ had “recognised the fear of Farage.” and offered to pay for a campaign manager.
He said the South Thanet seat would be “looked at and pored over very carefully” and said he was told during the 2015 campaign that spending was “perilously close” to the limit.
The prosecution’s case centred around claims some costs for activists and party workers were recorded as national rather than local election expenses, to ensure spending limits weren’t breached.
Declared spending came in under the £52,000 constituency limit, but prosecutors claimed more than £60,000 went undeclared.
Mr Mackinlay eventually won the seat, in what the court previously heard was a “nasty” election.
The MP’s agent, Nathan Gray, was acquitted on 13 December.
Mr Gray, 29, of Hawkhurst in Kent had faced one count of making a false election expenses declaration.