"I had several options for 2010, some of them with more established teams," the 27-year-old German said.
"Every driver has the same overall objective, to win the world championship one day, but the way I want to succeed is to be part of the process of building a team and to play a key role in developing the car.
"This is why the opportunity with Manor Grand Prix is so exciting for me."
British-based Manor, who have a strong pedigree in junior series, are one of at least four new teams due to enter the sport next season.
The team will hold an official launch later this year, with former Brawn sponsor Virgin expected to come in as a major partner.
Glock missed the last three races of the season due to an injury sustained in qualifying for the Japanese Grand Prix but took two podium finishes including second place in Singapore in September.
"I have spent a lot of time with (technical director) Nick Wirth, (principal) John Booth and other members of the team and what I liked most is that this a real racing team run by true racers," said the German.
"The team may be small and new but it has big ambitions and a very impressive car and development programme. I am confident that I can play a big role in terms of my technical input and that's a fantastic opportunity for me."
Wirth said he is delighted to have secured an established driver like Glock.
"To get a driver that has not only achieved podium finishes in 2009 but has such proven talent and the potential to take us forward for many years is very exciting," he said.
"The fact that he has come and seen all aspects of the project before making his decision speaks volumes about what we have achieved so far."
Wirth said progress on the new car is encouraging, with the first fully-finished monocoque completed a week ago and crash testing on all areas carried out since May.
"I think we'll have the bulk of the official FIA tests done by Christmas, bang on our schedule," he added. "Now we just can't wait to get Timo into the new car once track testing begins next year."