The Glasgow company, part of the wider Forrest Group owned by Celtic Football Club shareholder Chris Trainer, said it was taking on a further 120 panels across the country.
Those sites were owned by Forrest but operated by Clear Channel under a lease agreement.
From March this year Forrest is taking them back in-house and plans to replace the traditional paper and paste billboards with modern internally illuminated and digital signs.
Among the sites involved in the overhaul are Great Western Road in Glasgow and Fenwick Road in Giffnock.
The redevelopment work is scheduled to be finished by the middle of the year and Forrest said the move would give it 52% of premium Scottish outdoor market sites.
Marc Keenan, managing director, said: "Forrest know our territory better than anyone, being the only Scottish-based out of home media owner.
"We pride ourselves on our reputation for developing stand-out sites, which deliver the right audiences for our clients' brands. We have carefully developed our portfolio over the past 25 years and we are now ready to merge these locations with what is effectively a portfolio of similar scale."
Recent research from the Outdoor Media Centre said revenue in the sector grew 9.5% in 2012 to £970m.
Mr Keenan added: "Looking at forward growth, 2014 promises to be a very exciting year for Scottish media, with the independence referendum, the Glasgow Commonwealth Games and the Ryder Cup."
The most recent abbreviated accounts for Forrest Group, covering the 2011 calendar year, show a retained profit in excess of £750,000.
Mr Trainer sold outdoor advertising business Trainer Ltd to Scottish Radio Holdings in 1999 as part of a £27.5m deal. He later bought back part of the company with Mr Keenan.
Forrest Group has interests in property development, media, renewable energy and signage.
Last week Mr Trainer transferred more than eight million Celtic shares to his Forrest Securities business.
At that time Celtic said that through direct and indirect holdings Mr Trainer retained an interest in 10.78% of the ordinary shares and 9.33% of the voting rights of the company.