The cuts follow the announcement of the closure of several of The Observer's monthly magazines, announced last night (10 November).
GNM has around 1,700 staff working across its entire operation. The publisher has entered into a voluntary redundancy scheme. Commercial staff impacted by the cuts are expected to be informed of their fate within a month.
In addition, GNM said the Guardian's Thursday Technology print supplement will cease publication at the end of the year and will become an online-only offering.
GNM has already made a number of cuts to its operations this year. Its non-editorial department was hit by 80 job losses and 25 jobs went at the Guardian Print Centre in London.
Managing director Tim Brooks said the "vast majority of staff will still be working here, building the future of our cherished and unique journalism".
Guardian editor Alan Rusbridger, meanwhile, spoke about the new-look Observer, which will hit news-stands early next year describing it as "true to the traditions" of the paper.
Rusbridger told staff: "Nine out of 10 people will still be here at the end of the review".
Meanwhile, Guardian Media Group chief executive Carolyn McCall flagged solid performances elsewhere within the company. She told staff that Emap, its business-to-business joint venture with Apax Partners, made an operational profit of £40m for the first six months of the year.
She said: "If we do the right things now, which I believe we are doing, GNM and its journalism will continue to enjoy both security and stability.
"At GMG we are confident about the long-term prospects of our portfolio of businesses and investments, and about the cash we have - and will have - to support GNM.
"We have not, and will not, cut journalism that is fundamental to our core purpose and values.
"And neither is this about plain survival - our sights are set on more ambitious goals than just continuing to be around. GNM will need to continue to innovate, to challenge, to excel and - in some areas - to grow.
"We are midway through a process that - while not shielding us entirely from the pressures of a new and very tough media world - will enable us to look ahead with confidence."