The decision will in effect limit supply from 2022-23, although CEO Ivan Glasenberg said a price impact would likely come from the decision.
"I believe it will put pressure on the price," he said during the 2018 results presentation.
The cap will be around 150 million tonnes a year.
Despite an 8% higher year-on-year adjusted EBITDA of US$15.8 billion, the company's profits fell 41% compared to 2017 to $3.4 billion, or 24c per share.
The industrial side provided the EBITDA growth, with trading division earnings falling 17% year-on-year.
Shareholder returns came in at $5.2 billion for the year.
Glasenberg said dividends and buybacks would increase in 2019, even as uncertainty remained over conditions in the Democratic Republic of Congo and China manufacturing numbers soften.
"Our strong cash generation underpinned $5.2 billion of announced shareholder returns and buybacks in 2018," he said.
"Reflecting the strength of these cash flows, we are again recommending to shareholders a 2019 base distribution of 20c per share (~$2.8 billion), payable in two equal instalments in 2019.
"We also announce today a new $2 billion buyback programme, which will run until the end of 2019.
"We will proactively look to top this up (in August, or otherwise) as market conditions support, including automatically from a targeted $1 billion of non-core asset disposals in 2019."
The Katanga operation, run through the TSX-listed subsidiary, was also a weakness
BMO analyst Edward Sterck said every commodity division but one had missed expectations.
"Except coal (+2% vs. BMO), EBITDA for all of the major divisions came in below forecasts, with marketing missing by 8% due to lower margins and nickel and ferroalloys missing by 7% and 8%," he said.
Glencore said low inventories and rising demand among base metals would boost its trading outfit's returns in 2019.
Cobalt and copper production in the DRC were hit by the uranium content at Katanga and the move to sulphide ores at Mutanda, which will see Glencore cut production to 100,000t copper in 2019 while it studies plant options.
Glasenberg said it would try and negotiate its way out of paying higher taxes and royalties under the new DRC mining code, and this would be very influential on the sulphides investment decision.
Last month, at Mining Indaba DRC mining department chief Joseph Ikoli Yombo Yapeke was very clear with Barrick Gold CEO Mark Bristow the law would stand.
Glasenberg said the coal production cap was part of the company's climate change policy, which could also see it dropping its support of the World Coal Association.
"Our commodity portfolio and its key role in enabling the energy and mobility transition for a low-carbon economy enables us to look ahead with confidence and to remain focused on creating sustainable long-term value for all our shareholders," he said.
In the presentation, the CEO said he saw a tightening of the seaborne coal market as a result of the decision.
He said there would be some replacement from Russian and lower-quality Indonesian supply but this would not match demand from countries like India, Pakistan, Vietnam, Bangladesh and Malaysia.
He also flagged fewer tonnes exported out of South Africa as Eskom's plant-feeding mines run out.
The production cap was met with frustration in Australia, where Glencore just spent $2.7 billion on new assets.
Resources minister Matthew Canavan said it was "basic self-serving nonsense".
"Of course they don't want to let others in," he tweeted.
Australian Financial Review columnist Matthew Stevens said Glencore had "buckled" and "bowed" to climate lobbyists, namely the Church of England and Climate Action 100+.
The Church of England Commissioners' head of responsible investment Edward Mason celebrated the move, saying he was "delighted the Church Commissioners have led this Climate Action 100+ engagement".
