Capt Seath, originally from Cowdenbeath in Fife but based in Plymouth, Devon, suffered a suspected cardiac arrest while running the 26.2-mile course on 24 April and later died in hospital.
The Afghanistan veteran had been running for Help the Heroes.
The #SkydiveForDave challenge raised cash for the newly formed Captain David Seath Memorial Fund, which provides financial grants through Help for Heroes to wounded, injured and sick service personnel and veterans of the British armed forces.
Nine people took part in the tandem skydiving at Netheravon Army Parachute centre, including Capt Seath’s aunt and uncle, Morag and David Tunstall, from Dunfermline.
The challenge was organised by Major Pete Alexander, who served with Capt Seath in Afghanistan and was one of the skydiving instructors on the day.
Maj Alexander said: “I wanted to organise an event that would challenge people, take them out of their comfort zone and learn something of the courage Capt Seath displayed in his day-to-day life as an army officer.
“The event was a resounding success and the biggest thank you must go to all who took part. They have raised an incredible amount of money to provide support to our servicemen and women.”
His wife Lizzie, who also took to the skies, added: “ I wanted to do something in his memory and help raise money for the Captain David Seath Memorial Fund.
“It was a fantastically sunny day, perfect weather and it was a privilege to spend the day with Capt Seath’s family.”
In a statement, Capt Seath’s aunt and uncle said they hoped to continue his legacy. “After David’s tragic death in April, we wanted to do something that was reflective of him and his enthusiasm for life,” they said.
A total of 154 financial grants have been provided so far through the memorial fund to Help for Heroes.
Speaking after Capt Seath’s death his girlfriend Gaby Schoenenberger 29, a fashion designer based in Edinburgh, said it had left a “devastatingly large hole” in their lives.
She wrote on Facebook: “I cannot begin to describe the pain that I, his family and friends are feeling right now. It doesn’t make sense, and a character like his being taken away so viciously leaves such a devastatingly large hole in our lives.”
She went on to thank friends for their support.