Compass Point Estates bought the park from administrators KPMG earlier this month after it went into administrative receivership.
A new company The Portland (Weymouth) Ltd has taken over the running of the hotel complex, now called The Portland Hotel.
Compass Point Estates chief executive officer Lee Paul vowed to concentrate on the ‘business’ aspect of the park.
But he also revealed further plans for the site, including a proposed events showground and new buildings.
Meanwhile new hotel bosses Darren Gadd and Merv Turner are promising a transformed restaurant and more affordable rooms – plus 45 new jobs.
Compass Point Estates specialises in purchasing and developing former Ministry of Defence (MoD) properties – mainly into business parks.
Former MoD employee Mr Paul was aware of Southwell Business Park after acting for former owners Ray Bulpit and Roy Haywood when they purchased it in 1996.
He said Compass Point Estates would seek planning permission for an events showground on the outside of the park. There are also plans to build several new units at the rear of the site and to improve the park visually.
But Mr Paul, who is based in Bournemouth, said focusing on the business side of the park – which will retain its current name – was crucial.
He said: “I think it’s fair to say some people took their eye off the business side and concentrated a little too much on the hotel.
“We’ve found operators to take on that element, leaving us to concentrate on the business side – the workshops, offices and industrial units.”
Further possible improvements for existing tenants include reduced overheads for insurance and utilities charges, Mr Paul said.
Compass Point Estates also hopes to introduce a co-operative of tenants, to enable more shared training between companies.
Mr Paul, who has headed the firm for six years, added: “It’s been a difficult time with the recession, but I think we’re out of the worst.
“Now it’s just a matter of being flexible and cost effective with businesses, allowing them to grow and take advantage of the facilities.”
A KPMG spokesman said: “Southwell Business Park and its subsidiaries went into administrative receivership on March 17. The site was sold on March 18.”
Former Southwell Business Park co-owners Mr Bulpit and My Haywood were unavailable for comment.