Dennis, the unlikely saviour of the book printer, which was closed on 26 April by former owner MPI, saved the company following a dramatic last minute bid as the auction liquidating the company closed last month.
He said: "It was the superb print quality of my own book, Island of Dreams, produced by Butler & Tanner in 2007, that brought the company to my attention, so we are extremely pleased to finalise and secure the future of this unique printing company.
"We strongly believe that book and corporate publishers in the UK will seize the chance to reduce the carbon footprint of their publications by working with Butler, Tanner & Dennis, rather than in Asia and other faraway places."
Kevin Sarney, who worked tirelessly to save the company, despite the rejection of an initial bid by administrator UHY Hacker Young, has been appointed managing director with Ian Leggett, group finance director of Dennis Publishing becoming deputy chairman and Dennis taking the helm as chairman.
Eighty staff will initially be employed at the company, although in an open letter to previous employees, customers and suppliers, Dennis said he hopes this figure will "rise substantially in the months to come".
The letter added that the company now has his full financial support and the company is now "adequately financed" with all machinery secured and further finance available where appropriate. The business will continue to trade from its Frome premises.
He added that he wished to "re-establish a company of which Joe Tanner would have been justly proud".
Ann Field, Unite national officer said: "Unite welcomes the news of the re-launch. It is a modest start to what can be a prosperous future with greater job opportunity. With the support of the new owner and the commitments being given we believe this is a very firm vote of confidence in the workforce.
"It is also a step towards re-establishing quality colour book printing in the UK. This is great news and we will be giving every support to the workforce in their efforts to re-establish Butler, Tanner & Dennis."
Tony Burke, assistant secretary general of Unite, added: "This is good news for our members who lost their jobs and good news for the community in Frome."