Eurostar said it was running a full timetable of services throughout Monday, but passengers should prepare for delays of between 30 and 60 minutes as it juggles services through the single tunnel.
A spokesman said: "We are resuming a full service. Obviously because the Eurotunnel is closed due to the smoke on Saturday, there will be delays of between 30-60 minutes. We have had three departures today by 8.30am from the UK, St Pancras, which is as per normal. Most of the services were of relatively full capacity."
The backlog of those stranded at the weekend was cleared on Sunday night and Monday morning, the spokesman said.
Freight services also resumed early Sunday between England and France in the south tunnel, said John Keefe, the spokesman for tunnel operator Eurotunnel. He said the freight train affected by Saturday's incident had been removed from the tunnel to the French side, but the section where it was stopped remains closed. The tunnel is having to run a "traffic light system", with the line open to trains heading from Britain to France for 90 minutes, before it switches to trains heading the other way.
Mr Keefe said Eurostar passenger services are being given priority, but that delays will take place. Services that carry road freight through the tunnel face longer delays – as long as four hours. Heavy goods vehicles are being encouraged to take ferries instead.
Eurotunnel workers hope to reopen the closed section of tunnel on Tuesday morning, allowing services to return to normal.
Eurostar has said tickets can be refunded or rebooked within the next 60 days for travel within six months.