Separately, it was also confirmed the Glasgow agency has recently amicably wound down its nine-year working relationship with Celtic.
The SPFL deal is for an initial 12-months and is said to have been awarded following a competitive pitching process.
SPFL chief executive Neil Doncaster said: "BIG had an immediate grasp of the challenges and opportunities we face as a league and a clear vision of how we should tackle them.
"They have a great track record in sport and the fact that they previously worked with clubs such as Celtic and Aberdeen, as well as managing last year's highly successful Scottish Communities League Cup campaign means they can hit the ground running."
BIG director and co-founder Alex Barr handled the public relations campaign around the formation of the SPL in 1998 then handled media affairs for the league until 2004.
Mr Barr, who will work on the SPFL account along with BIG's head of sport Brian Welsh, said: "The SPL was one of the very first accounts we won when we set the business up in 2000 and it's a huge boost to have it back.
"This is an exciting time for the sport in Scotland and we can't wait to get started."
BIG is often described as the largest public relations agency outside of London.
In its most recent set of accounts, which covered the 12 months to May 31, 2012, BIG's pre-tax profits increased from £707,414 to more than £1 million, with turnover rising 4.6% from £6.15m to £6.43m.
The agency, which employs around 100 people, operates across offices in Aberdeen, Edinburgh, Kirkcaldy, Glasgow and Liverpool.