Commonwealth Games medallist Smith, who competes in the women's 58kg category, was the only British lifter to hit the top level Olympic selection standard and will be the youngest in the team aged just 18.
Former national karate champion Natasha Purdue, whose dreams appeared to be over after she failed to register a lift at the recent British Championship, will compete in the women's 68kg event.
The 36-year old was chosen ahead of both Jo Calvino or Emily Godley, who achieved the Olympic B standard at both the British and European Championships.
“I can’t describe in words how happy I feel and I keep pinching myself to make sure I’m not dreaming," said Purdue.
"I waited two weeks for the call, and when it came I didn’t want to answer it in case it was bad news.
"I asked them to repeat it about three times just to make sure."
The squad is completed by Gareth Evans, who gave up his job as a painter and decorator to focus on earning his place in the men's 69kg category, 21-year old rising star Jack Oliver, who competes in the men's 77kg, and Commonwealth Games silver medallist Peter Kirkbride in the men's 94kg.
“I am convinced we will participate at London with our strongest and best prepared team," said Team GB's weightlifting head coach Tamas Feher.
"Our five young strong-bodied and strong-minded athletes will show to millions around the world and in their own country exactly what it means to be a British weightlifter.
“The final stage of qualification was hard, and all involved competitors did their best. There was a lot of sweat, pain and sacrifice, which is usual with weightlifting.
"But now all team members are ready for the hardest 50 days' work of their lives to make sure they put in their best performance ever in front of their own fans.
“I have great pride in being their head coach and preparing and coaching such great athletes like ours.
"We have a great team in which all athletes support each other and I am sure they will give unforgettable moments to all Team GB fans and will push British weightlifting even further forwards.”