The 28-year-old was one of two people on board the plane, the other being the pilot, but it lost contact with air traffic control near Casquets lighthouse – around eight miles north-west of Guernsey in the English Channel.
The light aircraft which is understood to have departed Nantes, France, for Wales, UK, vanished from the radar off Alderney in the Channel Islands on Monday evening.
Argentine striker, Emiliano Sala, completed a £15 million ($19m) move to Cardiff City on January 19, having netted 12 Ligue 1 goals already this season.
Cardiff expressed serious concerns on Tuesday morning about his whereabouts.
“We are very concerned by the latest news that a light aircraft lost contact over the Channel last night.
“We are very concerned for the safety of Emiliano Sala,” the club said in a statement.
A coastguard rescue helicopter and the RNLI joined the hunt for the missing plane on Monday, despite the disappearance occurring outside of the UK search and rescue area.
A statement released by Guernsey Police read: “A search and rescue operation is currently underway off the north of Alderney after a light aircraft disappeared from radar several hours ago.”
The initial search was terminated at 3 a.m., with all rescue assets stood down amid strengthening winds and poor visibility.
The search was resumed on Tuesday morning when conditions improved.