The 150-year-old group, which is named after its Scots-born founder, reported a profit on ordinary activities before tax and exceptional items of £11.2 million for 2018, compared to £1.5m a year earlier. At the bottom line it made a profit of £6.7m compared with losses amounting to £34.2m in 2017.
The positive outcome came despite turnover, including the group's share of joint ventures, falling to £788m from £852m the year before.
Cash balances were £73m at year end, up from £66m, with no debt, the firm added.
Bosses said the positive set of results demonstrated the group's robust performance against the backdrop of a "highly competitive" UK construction market, which has suffered amid the fallout from the 2016 Brexit vote as several big projects are put on hold. They pointed to the firm's substantial cash balances, lack of debt and a "healthy" pipeline of work.
In 2018, the company successfully delivered a portfolio of projects for its clients across the UK. In its Scotland and Northern region, the group built student accommodation at the University of St Andrews and a new submarine paint facility at Barrow-in-Furness in Cumbria.
The firm also commenced the refurbishment of the St Enoch shopping and leisure centre in Glasgow, more than three decades after building the original.
The Hertfordshire-headquartered company said it was working to a five-year strategic plan introduced by current chief executive Paul Hamer at the end of 2018 which sets the path for Sir Robert McAlpine to realise its ambition to become "the best place to work" in the construction industry and "Britain’s best builder".
Hamer said: "This performance, alongside continued financial resilience and a healthy secured pipeline of work, represents a solid stepping stone for the business. Our strategy will continue to focus on working with clients who share our business values and to prioritise profitability and risk mitigation over turnover growth.
"With our new five-year strategy in place, we have the opportunity to build on our strengthening performance as we work to deliver on our ambition to become the best place to work in the construction industry and the best builder in the UK."