Greencoat UK Wind bought a 51.6 per cent stake in the North Rhins Wind Farm in Dumfries and Galloway and the Drone Hill Wind Farm in the Borders, along with two in England, for a total of £90.6 million.
It acquired the farms from the AES Corporation of the USA, which has developed generating assets across the UK.
The purchase will double the size of Greencoat's portfolio in Scotland.
Greencoat operates the giant Braes of Doune windfarm near Stirling and the smaller Carcant facility in the Borders.
The acquisition will increase Greencoat's investment portfolio to 16 UK wind farms, with total net generating capacity of 271.5 MW.
This is enough to power more than 200,000 homes.
The deal comes five months after Greencoat highlighted a strong performance by the 36-turbine Braes of Doune windfarm.
In March Greencoat said it had generated eight per cent more than targeted in the nine months to December.
The company said the Braes of Doune farm, of which it owns half, was the biggest contributor.
Both farms in Scotland generated more than budgeted in the period.
The company provided evidence that investing in wind farms can be a profitable business in its annual results.
It generated £21.6m cash after expenses between December 4, 2012 and the end of 2013. In November, chairman Tim Ingram said the opportunities lying ahead for UK Wind were very exciting.
He said the company aims to provide investors with long-term, predictable returns and to enable wind farm owners to free up capital.
The formula appears to be attractive to some investors.
Greencoat listed on the main market in London at the end of March last year and raised £260m to buy a seed portfolio of six UK wind farms from Scottish HyrdoElectric owner SSE and RWE.
The company says Greencoat UK Wind was the first renewable infrastructure fund to list on the London Stock Exchange main market.
Greencoat raised £83m in November through a share placing to help it continue building its portfolio.
Greencoat said then it had identified an acquisition pipeline of more than 400MW of UK investments and that it was doing due diligence on a number of potential targets.
The 11-turbine North Rhins Wind Farm is on the North Rhins peninsula, west of Stranraer, and has a total capacity of 22.0 MW. It has been operational since December, 2009.
The 22-turbine Drone Hill Wind Farm is located west of Eyemouth and has a total capacity of 28.6 MW. It has been operational since August, 2012.
The assets being acquired from AES also include the Sixpenny Wood Wind Farm in the East Riding of Yorkshire and Yelvertoft Wind Farm in Northamptonshire.
Greencoat said the deal would be financed from its cash resources and an acquisition debt facility provided by Royal Bank of Scotland, Royal Bank of Canada and Santander.