Ukip leader Nigel Farage conceded his party had been defeated during the by-election, but hailed the result as Ukip's "strongest ever by-election performance".
Speaking after the result, Mr Farage said: "I think there'll be an awful lot of Conservatives with a majority of less than 10,000 who will look upon this result in sheer horror."
But he admitted he would have liked to have done better in Newark.
"Yes, I mean the majority's halved, but nonetheless for Ukip it's still a good night's work," he said.
Prime Minister David Cameron has 'Tweeted' after Robert Jenrick was confirmed as the new Conservative MP of Newark, saying he will work to deliver a "brighter future".
David Cameron has hailed the Newark by-election result as "very good for the Conservative Party" but he said the Tories needed to "work between now and the next election" to win back voters from Ukip, who came out second in the by-election.
The PM was speaking in Bayeux, France ahead of D-Day commemoration events.
Asked how he would win back support from Nigel Farage's party he acknowledged the challenge posed by Ukip:
"The job isn't finished yet but we are on the right track, let's stick at it."
After the Conservatives win in the Newark by-election, Labour candidate Michael Payne has revealed he will push Robert Jenrick all the way "to the General Election."
Robert Jenrick, the Conservative candidate, won the Newark by-election with Ukip coming in second and Labour in third.
Speaking this morning, Labour's candidate spoke of how proud he was of his party's campaign during the by-election.
He said: "While this was always going to be a tough by-election, I am extremely proud of the campaign that Labour has fought.
"In the months ahead, I'll continue campaigning on those issues and holding Robert Jenrick to account right the way through to the General Election."
Robert Jenrick has been speaking after his victory in the Newark by-election.
Mr Jenrick won the seat with a majority vote of over 7,000 and said:
"Of course we're aware of national issues but what we wanted to show - and I think people recognise this - was that in a Westminster election you're choosing someone who'll be a great constituency MP for Newark and that's obviously what I aspire to be."
The Conservative's Robert Jenrick has won the Newark by-election with a majority of over 7,000.
Other candidates scored the following votes:
Nick the Flying Brick (The Official Monster Raving Loony Party) - 168
Andy Hayes (Independent) - 117
David Bishop (Bus-Pass Elvis Party) - 87
Dick Rogers (Stop Commercial Banks Owning Britain's Money) - 64
Lee Woods (Patriotic Socialist Party) - 18
Robert Jenrick saw off the threat from the eurosceptics to win the parliamentary seat for his party, but the Tory majority was cut significantly from from 16,152 to just 7,403.
Ukip surged from a distant fifth in 2010 to second, pushing Labour into third place while Liberal Democrat support was obliterated, leaving the candidate trailing in sixth place
Ukip MEP Roger Helmer increased the anti-European Union party's support from just 1,954 votes in 2010 to 10,028.
The Conservative Party has held the Newark seat vacated by Patrick Mercer.
Robert Jenrick has taken the seat with 17,431 votes.