Here, the PA news agency looks at what the new Baggies boss needs to tackle.
Keep Albion in the Premier League
Top-flight survival is ultimately the reason why the Baggies decided to sack Bilic and appoint Allardyce.
Bilic garnered sympathy as he was working with a squad which lacks serious Premier League quality and pedigree and Allardyce must find an extra gear.
Tighten up the defence
The Baggies have conceded the most goals in the Premier League – 26 – this season.
Sam Johnstone’s stunning performance helped them to a surprise 1-1 draw at Manchester City in Bilic’s last game but they cannot rely on the goalkeeper to deny all comers.
Albion have kept two clean sheets this season but Allardyce will need to drill more discipline into them.
Work with the board
Bilic was upset Ahmed Hegazi was sold to Al-Ittihad against his wishes in October and his relationship with the Albion hierarchy was fractious.
There was a gap between the management and the board and Allardyce must bridge it to ensure a more harmonious camp.
Convince January reinforcements to join
Albion have gone for a fire-fighting appointment and Allardyce has only got an 18-month deal, making it more difficult to sell a serious long-term plan.
The club went over their modest £20million budget in the summer so money will be tight for anyone Allardyce wants.
Also, given their position, any player who joins must understand they are likely to be in the Sky Bet Championship next season.
