Jorginho’s first-half penalty was enough to give Chelsea victory in a derby encounter they totally dominated.
The midfielder slotted home from the spot after Timo Werner had been fouled by Eric Dier near the right-hand edge of the area.
Tottenham improved after a dismal first-half showing but still rarely troubled the Blues, whose win lifted them to sixth in the Premier League table.
The visitors always looked a threat going forward – and keeper Hugo Lloris denied them a second goal by diving to his left to push away Mason Mount’s low shot.
Spurs’ best opportunity of the game fell to Carlos Vinícius, who missed a late chance to equalise when he headed wide from Serge Aurier’s cross.
Chelsea are yet to concede a goal under Thomas Tuchel, having won two of his opening three games in charge.
On a less positive note for them, veteran defender Thiago Silva went off injured during the first half.
Chelsea: Mendy, Azpilicueta, Silva (Christensen 36), Rudiger, James, Jorginho, Kovacic (Kante 73), Alonso, Hudson-Odoi (Pulisic 65), Mount, Werner.
Subs not used: Kepa, Abraham, Giroud, Chilwell, Ziyech, Emerson.