The airline also ordered 35 Boeing 787 Dreamliners and 10 Boeing 777s, in a deal the American company said was worth $9.4bn.
The deals at Farnborough come amid a difficult time for the aviation industry, with overheads increasing in the face of record oil prices and the rising cost of precious metals.
Tom Enders, Airbus's chief executive officer, said competition to win fresh orders from carriers was "hard fought" and "tough".
Oil wealth
Airlines in the Gulf have been well-placed to invest in large fleets, given that the Gulf states possess considerable oil wealth.
"The size of our order... mirrors the rising prominence of the Middle East and its increasing emergence as a new focal point of global aviation," James Hogan, chief of Etihad, said.
Etihad's investment in new aircraft comes after a concerted push by other carriers such as Qatar Airways and Emirates of Dubai to increase the size of their fleets and win over customers from longer-established airlines.
Boeing also won an order for 50 single-aisle 737 passenger aircraft from Gulf-based start-up carrier FlyDubai in a deal worth $4bn.
The Farnborough air show also presents aerospace companies with an opportunity to secure deals for military aircraft.
But noticeably absent on day one was the French defence industry, with many executives staying at home for a Bastille Day parade.
Aircraft builders are facing a challenge to improve the fuel efficiency of its models amid the rising cost of oil.
Airbus is promoting the A380's fuel efficiency and low emissions, touting the passenger capacity of the "super jumbo" as a key consideration for carriers.
Boeing says 525-seat aeroplanes are not in demand by most carriers.
Meanwhile, Bombardier has launched plans to take on Airbus and Boeing in the market for planes with over 100 seats.
It launched a 110-130 seat jet, the CSeries, on Sunday.