Boyce, 26, became Burton's record signing when he signed on a three-year contract from Ross County in June.
But the Brewers say the Northern Ireland forward will miss "most of the season" with a ruptured anterior cruciate ligament in his left knee.
The injury was sustained during a 1-0 pre-season friendly defeat by Shrewsbury on Saturday.
Boyce was the Scottish Premiership's top scorer with 23 goals last season, but is yet to make his competitive debut for Burton.
Nigel Clough's side, who are also without striker Luke Varney, begin their Championship campaign at home against Cardiff on Saturday.
Boyce, who formerly played for Irish Premiership side Cliftonville and German outfit Werder Bremen, scored his first international goal in Northern Ireland's 1-0 friendly win over New Zealand in June.
The injury will rule him out of Northern Ireland's remaining four World Cup qualifiers in September and October, as well as any potential play-off in November for a place at Russia 2018.
Burton Albion striker Liam Boyce will not play for most of the season after suffering a serious knee injury.