The event, organised by Littlehampton Town Council in partnership with Harbour Park, will take place on June 30 between 10.30am and 4.30pm on the seafront greens.
The event, one of the largest on the south coast, will begin with a seafront parade and a Drumhead Service on the green.
The rest of the day will be filled with arena displays, band performances, a charity fair, military vehicles, stunt display, memorabilia, a BBMF flypast and an aerobatic display.
Ian Buckland, chair of the community resources committee, said: “The Armed Forces Day charity fair is a fantastic fundraising opportunity and a great way to raise awareness and much needed funds for services charities.”
The organisers are looking for uniformed groups and collectors of military memorabilia to run pitches on the day.
Anyone interested in taking part can apply online at www.littlehampton-tc.gov.uk or phone 01903 732063 for more information. The deadline for bookings is March 26.