Allardyce's future at Upton Park is unsure, with his current deal expiring at the end of the season, although O'Neil admits that the players are hoping he stays at the club.
O'Neil believes that the former Bolton Wanderers boss deserves credit for the job he has done with the Hammers and claims that the players "long working for him".
"I think the gaffer has done a fantastic job. Teams that went down to the Championship last season like Bolton and Wolves have struggled," O'Neil told reporters.
"The job the gaffer did last year to get us straight back up and keep us clear of relegation is fantastic. The lads all love working for him.
"He's been great and we're trying to do the best job we can for him. The rate managers are sacked surprises me."
West Ham are currently 12th in the Premier League table.