Former world number one and 10-times Major champion Sorenstam is a veteran of eight Solheim Cups as a player and served as a vice-captain to Alison Nicholas last year in Dunsany, Ireland, where Europe beat the US 15-13.
Koch, 41, played in four successive Solheim Cups from 2000 to 2005, winning 11-1/2 points from 16 matches and sinking the winning putt for the European team as a rookie at Loch Lomond in 2000.
"I am extremely pleased to announce that Annika and Carin will be my vice-captains," Neumann, who has won 27 tournaments worldwide including the 1988 US Women's Open, said in a statement on Tuesday.
"Their passion for the game of golf and experience as past Solheim Cup players will prove invaluable as we work together to defend the Cup and win on US soil for the first time."
Sorenstam, widely regarded as the greatest female golfer of all time, was delighted to be given the chance to support Neumann, who was one of her early role models.
"Lotta has been a friend of mine for nearly 20 years and actually inspired me to follow my dreams when she broke through and won the US Women's Open in 1988," said the 41-year-old Sorenstam.
"I have always respected her class and demeanour and I know she will be a great leader for Team Europe. I look forward to helping Lotta in any way possible."
The 13th edition of the Solheim Cup will be played at Colorado Golf Club in Parker, Colorado, from August 16-18 next year.
The Europeans, who have never won on U.S. soil, trail 4-8 in the biennial series, which is the women's equivalent of the men's Ryder Cup where the top players from the United States face those of Europe.