Known for his straight-talking style, Lambert was given the nickname "gobby" for his tendency to shout questions to politicians.
Lambert, who takes over from Patrick O'Flynn in the role, said: "Over the past few years I have been following the work of UKIP and Nigel Farage and I feel that he is changing British politics for the better. I am delighted to be able to add my experience to his team. He has been one of the best, most hardworking and most normal political figures I have worked with, and trust me I have seen the lot.
"UKIP is today the place to be if you want to be a part of a party that is changing the face of British politics for the better, and providing a new, clear and honest voice".
Party leader Nigel Farage said: "I am delighted to welcome Paul to our team. Knowing him, and how effective he has always been in getting his message across, he will fit UKIP like a glove. Drive, passion, hard work, honesty and immense good humour are the hallmarks of Paul. It'll be fun working with him."
Despite the recent by-election success and growing support nationally, UKIP has continued to generate some negative press coverage with the outspoken views of senior figures.
Last week Farage was criticised when he suggested that women who breastfeed in public could "perhaps sit in a corner", although he hit back by saying some parts of the media misinterpreted his words.