As part of a new regulations to be introduced next year, drivers will carry permanent numbers in F1.
Every driver has been asked to choose their race number, between #2 and #99, while #1 will be reserved for the world champion should he want it.
The FIA has requested all drivers to nominate their preferred number, along with a second and third choice, to be lodged before Christmas.
Alonso said on Friday he will choose #14.
"I will use 14," Alonso told reporters in Madrid. "It has been my lucky number since 1996, when, while I was 14, on July 14 and with kart number 14 I won the world championship.
"Since then I have always used 14. Hopefully it will be lucky next year."
Alonso's new team-mate Kimi Raikkonen has chosen #7, while his former team-mate Felipe Massa will use #19 at Williams. His team-mate Valtteri Bottas has chosen #77.
Other drivers who have revealed the numbers they want include Nico Rosberg (#6, #5 or #8), Sergio Perez (#11), Jean-Eric Vergne (#21, #25 or #27).