Long-serving Group CFO James Rigney left the troubled airline along with CEO James Hogan in July.
Powers will join Etihad this month, the airline said in a statement.
He was CFO at JetBlue from 2011 until 2016, having joined the New York-headquartered airline as treasurer in 2006.
JetBlue has been critical of attempts by American Airlines , Delta Air Lines, and United Airlines to restrict the growth of Etihad and other Gulf carriers over accusations they receive unfair state subsidies. The Gulf carriers have denied the subsidy claims.
Powers will head the finances of Etihad Aviation Group (EAG) which oversees Etihad Airways, engineering, airport, travel services units, and its investments in other carriers.
"The Etihad Aviation Group Board believes Mark and the wider finance team will play a pivotal role in helping to guide Etihad onto the next stage of its development," said Group CEO Tony Douglas, who joined the airline this month.
Etihad reported a $1.9 billion loss for 2016, its first since 2010. Like fellow Gulf carriers Emirates and Qatar Airways, it has had to battle overcapacity, security concerns and a drop in regional business travel in recent years.
Etihad cut, or announced it was dropping, several routes last year including to U.S. cities San Francisco and Dallas.
On Monday, Etihad signed an aviation security pact with Emirates, the first such cooperation agreement between the two UAE-based rivals.
Etihad has also been hampered by stakes it has bought in more than half a dozen airlines.
Key investments Air Berlin and Italy's Alitalia both entered administration last year.
Etihad has sold its holding in Swiss-based regional airline Darwin but still has stakes in Virgin Australia, Air Seychelles, Air Serbia, and India's Jet Airways .
Powers takes over from Ricky Thirion who held the position in an acting capacity since July 1. Thirion will resume his role as group treasurer, Etihad said.
(Stanley Carvalho and Alexander Cornwell - Reuters)