The Scottish Professional Football League (SPFL) has announced that betting company Ladbrokes will be its main sponsor from next season.
The two-year deal, believed to be worth a little over £4m, includes rights across all four leagues and 42 clubs.
While it did not reveal any figures, Ladbrokes said the deal was the biggest of its kind in Scottish football.
The SPFL has been without a sponsor since 2013 when the league was restructured.
The Clydesdale Bank sponsored the Scottish Premier League until its contract expired two years ago, electing not to renew the £2m-per-year deal.
Funds from that were split between 12 clubs.
The new deal will result in the Scotland's leagues become known as the Ladbrokes Premiership, Ladbrokes Championship, Ladbrokes League 1 and Ladbrokes League 2 at the start of the new season in August.
An "absolutely thrilled" SPFL chief executive Neil Doncaster told BBC Scotland: "It is the biggest single ever title sponsorship deal of this nature in Scotland in 125 years of the Scottish Football League.
"So it's hugely significant, I think, financially.
"It's a deal across the whole of the SPFL - the first deal of its kind - and all 42 clubs will benefit through the ladder mechanism set out in the rules.
"On all those levels, I think it's great news for all clubs in Scotland."
The new deal takes the total SPFL prize-money fund to £20m.
Next season's Premiership champions will receive an additional £268,000 as a result, with the Championship winners receiving £45,000 more.
At the bottom end of the scale, the team finishing bottom of League Two will earn their club an extra £3,600.
"As much of a financial difference, there is a pride issue here," said Doncaster.
"To have a league sponsored with a company like Ladbrokes - a hugely respected blue-chip UK company - who want to sit alongside you and develop the game in Scotland is hugely significant as well.
"It all matters and, if you talk to individual clubs then I suspect they'll see it slightly different ways.
"But, from our point of view, it's a deal that benefits all 42 clubs and adds to the prestige of the league overall."
Doncaster was aware that the SPFL had received some criticism for the years without a title sponsor.
"It has not been the easiest time to go out and sell a title sponsorship," he said.
"We are well aware of some of the financial issues that have affected some of our member clubs over that period.
"But the reality is that we have had a number of big brands who wanted to partner with us.
"We have had various offers over the period that we've rejected, but the clubs' stance, which we think has been vindicated, was they wanted to wait for the right brand at the right money."
Ladbrokes chief executive Jim Mullen added: "We love football so we are delighted to be working with the SPFL on one of the best opportunities in British sport."