Emerton had ankle surgery after Sydney FC's A-League campaign but, despite getting some mobility back, is still on crutches and will be unavailable for the two qualifiers in Muscat (8 June) and Brisbane (12 June) as well as the friendly against Denmark on 2 June.
Cahill has not featured for the Socceroos due to a variety of injuries since coming on as a late substitute against Saudi Arabia last September.
The Everton man played an important part in the Toffees' strong end to the Premier League campaign but was sent off in the season finale against Newcastle on Sunday.
Aston Villa midfielder Chris Herd is the only new face after being included as part of the 26-man party along with 2010 FIFA World Cup squad member Nikita Rukavytsya, who has not played since March last year.
First-choice players Matt McKay, Luke Wilkshire, Brett Holman and Josh Kennedy are picked after missing the 29 February qualifier against Saudi Arabia, while the other players recalled compared to that squad are Nathan Coe, Adam Federici, Mile Jedinak, Neil Kilkenny, Robbie Kruse, Carl Valeri, Rhys Williams and Michael Zullo.
Melbourne Victory pair Archie Thompson and Harry Kewell are the only two A-League players included, with five cut from the most recent 19-man squad.
Coach Holger Osieck will reduce the squad to 23 players before the Oman game.