The production record was driven by increased production from the BHP operated Escondida mine that increased its production 34% to a record 1.2Mt.
Meanwhile, state copper company Codelco produced 1.7Mt, its lowest output since 2014.
Chile is the world's largest producer of copper and increased its market share to 27.7% of global production in 2018 from 26.7% in 2017.
The production of copper concentrates in Chile continues to increase with 73% of the country's production in this form and 27% as copper cathode.
Chile's production is set to grow even more in the coming years, according to Cochilco. "If the projects on the table are executed, we foresee production towards 2025 of seven million tonnes," said Cochilco EVP Manuel José Fernández.
Growth this year is expected from expansion projects at Escondida, Codelco and Spence, as well as at KGHM's Sierra Gorda operation.
Molybdenum production was 60,705t, down 3.4% from the 62,746t in 2017. Codelco produced 24,030t, its lowest output since 2013. The main bright spot was a 26.0% increase in production from Antofagasta Minerals' Las Pelambres mine to 13,352t from 10,597t.