The job cuts will cost between $10m (Â£6.5m) and $20m in severance pay, while the restructuring will cost between $5m and $15m, the company said.
Shares in Twitter rose 2% in pre-market trading following the announcement.
The move comes just days after co-founder Jack Dorsey was confirmed as Twitter's permanent chief executive.
He had served as the interim boss of the company for three months after Dick Costolo stepped down on 1 July.
Mr Costolo, who was chief executive from 2010 to this year, had been under pressure from investors unhappy with the firm's user growth.
In a letter to Twitter employees, Mr Dorsey wrote: "We have made an extremely tough decision - we plan to part ways with up to 336 people from across the company.
"We are doing this with the utmost respect for each and every person.
"Twitter will go to great lengths to take care of each individual in providing generous exit packages and help finding a new job."
Mr Dorsey told employees: "Emails like this are usually riddled with corporate speak so I'm going to give it to you straight."
He went on to outline how the Twitter had been "working around the clock to produce streamlined roadmap for Twitter, Vine and Periscope" and described the company's latest innovation as "a bold peek into the future of how people will see what's going on in the world".
Twitter has said it is cutting 336 jobs, roughly 8% of its global workforce, as part of a restructuring of the business.