The agreement, initially to screen live League football, Worthington Cup and LDV Trophy games, will bring in £20m in the first season, which the League hopes will help save clubs facing financial difficulties.
The deal will deliver more than 300 live matches to Sky Sports by the end of the 2005-06 season with the first matches to be shown next month.
There could also be an agreement for a highlights package.
Hope for cash-squeezed clubs
The broadcasting rights for the games were returned to the Football League after the previous owner, ITV Digital, collapsed in April, owing the League £178.5m.
Before its collapse, ITV Digital had offered the league a £50m compromise deal for the remaining two years of the contract, but that offer was rejected.
Football's TV deals
2000: ITV Digital agreed £315m, three-year League deal
2001: Sky agreed £720m, three-year Premiership deal
2002: Sky agrees £95m, four-year League deal
A subsequent offer of £74m was also turned down.
Football League chief executive, David Burns, said the Sky deal should save League clubs from going under.
"The parlous financial state they were in has not been eased in total, but it certainly has improved immeasurably today.
"I think one or two clubs will have one or two financial difficulties. But do I think they will get out of the difficulties? Yes, I do," he told BBC Radio 4's World at One programme.
But Mr Burns denied that the deal proved that ITV Digital had been wrong to offer so much for the original contract.
"They paid the market rate at the time, and in June 2000 the market rate was significantly ahead of what it is today."
Court action against ITV Digital
Sky intends to broadcast live matches on Saturday evenings at 5.35pm, along with some games on Friday evenings and Sunday afternoons.
Vic Wakeling, managing director of Sky Sports said: "We hope that the clubs can now plan for the future.
"We will soon schedule the first live matches, with the League and the clubs, so that fans can plan their opening weeks of the season."
The League said it would press ahead with legal action against the owners of ITV Digital - Carlton and Granada - at the High Court in London on 26 July.