Beckham crashed his shot home from 35 metres on the hour mark of what had been a moribund second round game played in sticky conditions at the Gottlieb-Daimler-Stadion.
Beckham, whose free-kick against Paraguay in their Group B opener was turned into his own net by captain Carlos Gamarra for a 1-0 win, became England's first player to score in three World Cups.
The practice was that England failed to create a single goalscoring opportunity in a scrappy first half and were lucky not to go in at the break a goal down
John Terry's [ Images ] poor headed interception after 11 minutes fell to Carlos Tenorio and the Ecuador striker had only keeper Paul Robinson to beat.
But Tenorio took a second too long and his deflected shot, under a challenge by Ashley Cole [ Images ], hit the bar and flew over.
Ecuador, who reverted to the side which beat Costa Rica 3-0 to reach the last 16, looked sharper with strike pair Agustin Delgado and Tenorio back in the side.
Edison Mendez was the next to give Robinson a fright with a fizzing free kick that ricocheted just wide of the post off Delgado.
England's passing, which was often poor before the break, failed to improve afterwards, though Ecuador were no more incisive.
Sven-Goran Eriksson's men, who seemed intent on boring the South Americans into submission, finally got the breakthrough when Beckham's free kick flashed past keeper Cristian Mora, grazing the inside of the post.
It brought the game to life and England were only let down by the final pass in their attempts to add a second on the break in the closing stages as Ecuador pushed forward.