Ghana's 20,000 fans, who had helped create a fantastic atmosphere, were sent absolutely delirious when Gyan's goal cancelled out Andy Carroll's late first-half strike for Fabio Capello's much-changed England side.
Carroll, who moved from Newcastle United to Liverpool for 35 million pounds in January but has hardly played because of injury, produced a killer finish with a low left-foot bullet after 43 minutes for his first England goal on his second appearance.
But Gyan, who plays his club football in England with Sunderland, produced a brilliant finish as the match moved into injury time, jinking his way into space in the box, selling Joleon Lescott a dummy, then finishing with a precise left-foot shot that gave goalkeeper Joe Hart no chance.
"It was a fantastic game," England coach Fabio Capello told ITV.
"I am happy because Ghana didn't play it like a friendly. "The two teams were really, really good, playing strongly with lots of tackles. I'm happy with the performance. The players played without fear and with confidence."
Carroll said: "It's great to be playing again and to have scored a goal. I enjoyed playing in the 4-3-3 formation. I'm here and ready to score goals if picked."
A crowd of more than 80,000 included the largest number of visiting fans for an international since Wembley re-opened four years ago and they gave vociferous backing to last year's World Cup quarter-finalists as England were made to work hard to stretch their unbeaten run against African opposition to 17 matches.
Ghana, who were playing an African Nations Cup match in Congo on Sunday before arriving in London on Monday, deserve huge credit for their positive approach.
SEVEN CHANGES
Capello made seven changes from the team that beat Wales 2-0 in a Euro 2012 qualifier on Saturday, and while there was some criticism of his selection before the match, his 4-3-3 formation acquitted itself well.
The breakthrough came after 43 minutes when Ashley Young and Stewart Downing combined before Downing allowed the ball to run on to Carroll who gave Richard Kingson no chance with a blistering finish.
Ghana had missed a great chance to take the lead in the seventh minute when Dominic Adiyiah, who scored on Sunday, fired straight at Hart.
The game fizzed along with attacks from both sides, before Young somehow contrived to hit the bar from two metres out.
Not even a flurry of second-half substitutions interrupted the flow but finally England, whose makeshift defence had done well, were unlocked.
Gyan, who will be forever remembered for missing the injury-time penalty that would have made Ghana the first African team to reach the World Cup semi-finals, now has a far more satisfying last-minute memory to look back upon.
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