Results for the year to March 31 2010 show turnover up to £46.3m while pre-tax profits hit £2m.
A healthy profit margin in line with company targets means Jones Bros will now invest in new plant in the coming year.
Managing director Huw Jones said: “We had another year of further solid progress, despite the economic recession and a very competitive market.
“A big area of expansion for us was the energy sector, where we worked for both renewables and conventional energy producers.
“We’ve also benefited from continued repeat business from a number of clients.
“Jones Bros, based in North Wales, is now a UK-wide operator, as our turnover is split fairly equally among projects in Wales, England and Scotland.
“Considering the ongoing uncertainties in the economy, we have a very healthy order book of work going forward, which will enable us to continue our expansion strategy to develop Jones Bros into a leading UK civil engineering operator.
“As part of that strategy, we’re going to be investing more in new equipment, to expand our plant fleet in the coming year. The future is looking very positive.”
The company is also looking to take on more staff to add to the current headcount of 265.
Jones added: “Virtually all of these employees live and spend their wages locally, benefiting the Welsh economy.”
The Ruthin-based business is separated into two companies, operating in civil engineering and plant hire. Jones Bros Ruthin Co Ltd owns both.
The firm specialises in highways and infrastructure construction and improvements; energy projects including renewables; construction of waste management facilities and waste remediation projects; and flood and coastal protection projects.
Jones Bros’ most significant project last year was a £19m contract to build the infrastructure for a 60-turbine wind farm in East Lothian for Fred Olsen Renewables. Other wind farm work included completion of Carno 2, mid Wales, and commencement of Tullo wind farm near Aberdeen.
In Wales, it started the £6.8m coastal defence scheme at Tywyn, Gwynedd; and construction of an eco visitor centre at Aberthaw coal fired power station, South Wales, where is has ongoing infrastructure contracts.
The firm also started the construction of the £35m Porthmadog bypass in a 50:50 joint venture partnership with Balfour Beatty.