Albion have now confirmed the dismissal on their official website, with technical director Terry Burton noting that the decision came about through "regret but necessity".
"We appointed Alan in the summer convinced that we had taken on one of the foremost coaches in the UK and nothing that has happened since then has altered our view.
"The individual progress of our players such as Craig Dawson and Saido Berahino are testament to that. But sadly that simply has not translated into results and they remain the ultimate currency of Alan's position. Securing a sixth season in the Premier League is the over-riding target and sometimes unpleasant decisions have to be taken to serve that imperative.
"Alan has impressed everyone with his manner, dedication and diligence but he knows that results have simply not been good enough.We place on record our gratitude for his efforts and hold nothing but good wishes for his future endeavours. This was a decision taken with regret but sadly driven by necessity."
The 56-year-old replaced Pepe Mel at The Hawthorns in the summer, earning a 12-month contract ahead of his first job in Premier League management.
Despite producing a number of promising results early in his tenure, Irvine had overseen seven defeats in the Baggies' last nine league outings.
Tim Sherwood is among those touted to replace him in the West Midlands.