Mr Howie, best known for his self-titled butcher products including sausages, black pudding and haggis, said the food business has seen around a 20% increase in sales in the first quarter of this year.
That came on the back of the company having experienced a strong second half of 2012.
As a result the 60,000 sq ft site at Dunning, Perthshire is having an additional 10,000 sq ft added over the summer.
The workforce there had already risen from 90 to 105, with Mr Howie planning on taking on a further 15 people once the construction work is completed by the end of September.
He said: "As the volumes ramp up, you get economies of scale, which are good for the bottom line.
"It also gives you the opportunity to invest in equipment and machinery to handle that volume.
"The factory extension will give us more space. It is making sure we are not trading at 100% volume as we want be able to have spare capacity if something else comes along and this makes sure we don't have to outsource and can handle everything ourselves."
Mr Howie said sales have increased at the company's retail sites in Perth and Auchterarder and also through supermarkets where the food business supplies a number of the big players. He said: "I think most of the private retailers are seeing a decent upswing with some people temporarily moving [to traditional butchers] until things settle down.
"We are in the good situation where we don't supply own label brands to supermarkets and everything is done under our own name so we hope people are perhaps trading up to our products."
Vion's decision to close its Hall's of Broxburn operation is also thought to have contributed to the Simon Howie's Foods sales uplift in supermarkets.
Mr Howie, a previous winner of the Entrepreneurial Exchange's entrepreneur of the year title, said: "We are not quite sure whether our upturn in supermarkets is because of Hall's not being there or people trading up to the brand.
"It is difficult sometimes to be 100% sure but it has been a real bumper few months."
Howie's Shore Laminates business, based in Perth and a specialist supplier of laminated panels particularly for wash rooms, has also been performing well with a number of export contracts.
One of those, an education project worth £3 million in Saudi Arabia, was the largest in the company's history.
Mr Howie said: "Generally the green shoots are there now and there is a lot of good stuff happening across the group.
"Shore Laminates has won some nice contracts abroad and is doing the Doha Convention Centre and recently been awarded the fit-out of the wash rooms of the One World Trade Centre at Ground Zero [in New York]. It is not a huge project but we are extremely delighted to be part of something like that."
His Shore Energy business is still waiting on the outcome of a judicial review over plans for a £50m waste energy plant at Carnbroe, near Coatbridge in Lanarkshire.
The proposed facility was initially refused planning permission by North Lanarkshire Council.
The decision was then reversed by Scottish Government Reporters but the development has been subject to further legal challenges.
Mr Howie said: "We are very hopeful the outcome of the judicial review will be very positive. We are poised and ready to get on with that."