Werner’s first-half strike was enough to decide a tight derby in east London, with Fabian Balbuena shown a straight red card late on for a follow-through challenge on Ben Chilwell.
The result means Thomas Tuchel’s Blues are in the driving seat to finish in the Premier League top four after a week dominated by their entry to - and exit from - the controversial European Super League, while West Ham have plenty of work to do during the run-in.
West Ham, who kicked off behind Chelsea on goal difference, had every reason to be affronted at the proposed breakaway Super League given that they were above four of the six clubs involved when it was announced.
They were feeling hard done by again when a late VAR decision saw defender Fabian Balbuena shown one of the most ludicrous red cards of the season.
Nevertheless a favourable run-in means we may not have seen the last of David Moyes’ boys in the Champions League mix.
Additional reporting by PA.