Jordan Henderson had given England the lead 10 minutes earlier, and the Tottenham striker doubled it in first-half injury time.
With his third goal of the championships, Bukayo Saka capped the scoring in the shockingly easy victory after 57 minutes.
The following task for England won't likely be as simple because Kylian Mbappe and Les Bleus will be waiting for them on Saturday.
Only the number of times England wasted possession in risky situations throughout the tedious first half hour stood out, as Senegal failed to take use of their opportunities.
After Boulaye D'a's close-range drive missed John Stones and VAR determined there was no need for a penalty, Jordan Pickford was forced to make an outstanding save to stop the Salernitana striker from scoring from ten yards away.
Seven minutes before halftime, England finally awoke from their slumber and made their first play of true quality, giving them the lead. Jude Bellingham was given freedom by Kane in the left channel, and Henderson turned in his low cross.
Three minutes later, an almost identical play from the right with Saka slipping the ball across for Kane, who wastedly fired over the bar, could have made it 2-0.
The advantage for Gareth Southgate's team did double during first-half stoppage time, though. Bellingham, who was outstanding, won the ball on the outskirts of his own area, raced through midfield, and then found Foden on the left. Kane took a touch before smashing past Edouard Mendy after Foden slid it across for him.
12 minutes into the second half, England put the game beyond question. When Kane's pass was stopped, Foden seized the opportunity to deliver a centre pass to Saka, who deftly lifted the ball over Mendy.
Senegal had long since lost all of its life, but Southgate was still able to make some adjustments with France in mind.