The CBI said the world's fifth-largest economy would grow by 1.3 per cent in 2018, 1.4 per cent in 2019 and 1.6 per cent in 2020, little changed from its previous projections in June.
The forecasts were slightly weaker than those of the Bank of England.
The CBI said it was assuming that Prime Minister Theresa May wins backing in parliament for her preferred plan for leaving the European Union, something which looks unlikely at a vote due on Dec. 11.
"A no-deal scenario would blow these figures out of the water," the CBI's director-general, Carolyn Fairbairn, said, reiterating her organisation's support for May's plan.
Economists at U.S. bank J.P. Morgan said on Wednesday the odds of Britain staying in the EU had risen to 40 per cent from 20 per cent, following parliamentary setbacks for May and the likelihood that the European Court of Justice will rule that Britain could unilaterally revoke its EU departure notice.
Before the 2016 referendum, the CBI argued that staying in the EU would be best for Britain's economy.
Whilst the CBI expects real wage growth to recover partially, it predicts living standards will not rise much, due to Britain's failure to tackle persistently weak productivity.
"Brexit has sucked the oxygen from the domestic agenda," Fairbairn said.