Andrew Waterworth scored a second-half hat-trick as Linfield beat Cliftonville to clinch the title on a dramatic final day of the Irish Premiership season.
The 3-1 win at Solitude means David Healy's Blues end the campaign two points ahead of Crusaders who had held the title for the last two years.
Crusaders ended their title challenge with a 5-1 win over Glenavon at Seaview but in the end it was not enough.
It is Linfield's first title triumph since they did the double in 2012.
They are one match away from another double as they face Coleraine in the Irish Cup final on 6 May.
Linfield may have lifted the County Antrim Shield in February, but this will go down as a first major managerial success for Northern Ireland record scorer David Healy.
He took over as Linfield manager in October 2015 and saw his team end the season runners-up in the league and beaten by Glenavon in the cup final.
Clinching the title in his first full season seemed unlikely in mid-February when Crusaders were nine points ahead.
But Linfield went on an amazing run picking up 43 points from a possible 45, to take advantage of Crusaders' slip-ups.