The airline said the order is the largest in its history and “remains subject to the negotiation of a final purchase agreement”.
SilkAir said the firm orders will cover 23 Boeing 737-800s and 31 Boeing 737 MAX 8s.
The deal for the 54 aircraft is worth US$4.9 billion based on Boeing’s current list prices.
The B737-800 is the best selling variant of Boeing’s popular next generation family of single-aisle aircraft, and the 737 MAX is currently in development.
“Deliveries are due to begin in 2014 and continue to 2021, by which time the airline’s fleet will have more than doubled in size,” the carrier said.
SilkAir currently operates 21 Airbus A319s and A320s, with three more A320s due for delivery by the end of 2013. It said the new orders will cater for both growth and fleet renewal.