has become Great Britain's first Olympic judo medallist for 12 years, despite losing her gold medal match to American Kayla Harrison.
The London-born judoka
had to settle for silver
as Harrison landed two yuko scores in the -78kg final.
Gibbons, the world number 33, beat French world champion Audrey Tcheumeo in extra time to earn a place in the decider.
She was bidding to win Britain's first ever judo gold at an Olympics.
"Gemma deserves that silver medal. She hasn't lost the gold, she has won the silver. I can just imagine how she is feeling. She has had a fantastic day. She has come so close to the gold and will wish it was that little bit more."
The last British medallist was
Gibbons's coach Kate Howey,
who took silver in Sydney 2000.
Gibbons, 25, had beaten three of the world's top 10 on her way to the final, where she had to contend with another of the best judokas in the sport.
Harrison, the 2010 world champion, was aiming to win her nation's first ever judo gold medal and started the stronger.
She notched the first point of the final, a yuko, after a minute, landing Gibbons on her right shoulder.
The Briton attempted an audacious throw inside the second minute, but it was Harrison who scored with another yuko 30 seconds later, although, following protestations from Howey on the sidelines, the point was wiped out after judges ruled it had not been completed in one movement.
Gibbons was being cheered on by her partner, fellow Great Britain judoka Euan Burton, who
crashed out of the men's competition
Great Britain's Olympic judo silver medallists
- Gemma Gibbons (78kg)
- Kate Howey (70kg)
- Raymond Stevens (95kg)
- Nicola Fairbrother (56kg)
- Neil Adams (78kg)
- Neil Adams (71kg)
- Keith Remfry (Open)
- David Starbrook (93kg)
But the hometown player was unable to gain momentum and the American once again upturned her opponent and scored a yuko which this time stood.
Gibbons launched waves of sustained pressure inside the final 45 seconds, but Harrison adhered to the message bellowed from her coach Jimmy Pedro: "The gold medal is yours if you fight smart."
Harrison did just that, holding off the British charge to seal the win and the victory for the United States.
Gibbons's brave performance in front of raucous support at the ExCel will have won her many admirers - and capped a day of impressive and successful judo.
She beat Marhinde Verkerk from the Netherlands in the quarter-final following wins over Mongolia's Lkhamdegd Purevjargal and Portugal's Yahima Ramirez in the earlier rounds.
In a memorable moment after defeating Tcheumeo in the last four with an ippon, Gibbons broke into tears as she looked to the heavens, paying tribute to her mother, who passed away in 2004 after suffering from leukaemia, with the message: "I love you mum."
Watch the whole of the women's -78kg gold medal match