Up to 100,000 youngsters will be eligible for half-price day tickets using The Young Persons 16-18 card from September.
It was agreed by the area's mayor Andy Burnham and Transport for Greater Manchester, and a similar scheme is being considered for the Metrolink.
Hajrah Ahmed, 17, said half-price bus tickets "will be such a big help".
The Manchester College business student who travels to Openshaw from Cheetham Hill every day said her journeys are costing £100 per month.
"[It] is obviously an awful lot of money for someone like me, who doesn't have a part-time job.
"I can look ahead to the next year or so without the worry of how much money I am spending on my journey," she said.
The deal was proposed by Mr Burnham in his manifesto for mayor in April.
"I promised to help our young people get on in life, and this is the first step in delivering on that," Mr Burnham said.
Greater Manchester Travelcards Ltd, which represents all bus companies in the area, will extend its multi-operator 50% discounted 16-and-under ticket.
A junior day ticket to cover 16 to 18 year olds will also be introduced.
Eligibility to use the ticket will run up to 31 August after the user's 18th birthday.
Discounted bus tickets for 16 to 18 year olds will be rolled out in Greater Manchester, it has been announced.