On the second anniversary of Stephen's death, the charity has also outlined how the cash has aided cancer services for young people.
Stephen died on 14 May 2014, after contracting bowel cancer.
The 19-year-old, of Burntwood, Staffordshire, became well known after posting a picture online of his "final thumbs up" from a hospital bed.
He had pledged to raise £1m himself for the charity and hit the target three weeks before his death.
The trust said £2.7m had been spent refurbishing cancer units at hospitals across the country, with four more - in Cambridge, Hull, Newcastle and the Wirral - now to benefit.
A total of £1.6m has been used to train specialist nurses, as well as fund the charity's International Conference and Adolescent and Young Adult Global Cancer Congress in December.
Stephen's legacy is also helping fund JTV Cancer Support, a project helping young sufferers express their feelings and record their personal journeys.
Around £500,000 has been spent on education and awareness programmes, and £200,000 on conference weekends for youngsters called Find Your Sense of Tumour.
Stephen's mother Jane has now been made an official ambassador for the trust.
"Not a day goes by when I don't miss my brave and brilliant son. But when I think about everything he achieved and how much he's helping other young people, it makes me feel so proud," she said.
"With his voice in my ear, I've run a marathon, jumped out of a plane and in a few months, I'll be climbing Mount Kilimanjaro.
"I'm honoured to call myself an ambassador for Teenage Cancer Trust, and feel privileged to be able to continue to spread Stephen's unique message of positivity."
Kate Collins, director of fundraising and marketing at the charity, said: "Stephen was the most incredible young man and has helped us take huge steps forward for young people with cancer."

Callum Cartlidge suffered a cardiac arrest at home after developing suspected sepsis, sources told the BBC.
Paramedics were allegedly told to take him 18 miles (29km) to Worcestershire Hospital and not nearby Alexandra Hospital in Redditch, which stopped admitting children to A&E in September.
The trust said it was investigating.
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Callum, from Redditch, had seen a GP on 28 February and was diagnosed with tonsillitis and a tummy upset and given antibiotics.
His mother Stacey said her son got worse and on 2 March a GP sent him to Worcestershire hospital.
She said he was discharged at 23:00 GMT and she was told to give him Calpol. He collapsed the next day and later died.
West Midlands Ambulance Service said the trust had previously told staff not to take patients under 16 to Redditch, after Alexandra Hospital's children's inpatient services were moved.
Sources claim paramedics, who suspected Callum had developed sepsis, wanted to take him to Redditch but were told they could not.
Three members of staff performed life support throughout the 23-minute journey to the hospital.
"Having reviewed the case, there is no doubt that the ambulance staff did absolutely everything possible to help the child," a service spokesman said.
Worcestershire Acute Hospitals NHS Trust offered its condolences to Callum's family.
"As with any sudden unexpected death in childhood there will be a referral to the coroner, a post-mortem [examination] and a full external Sudden Unexpected Death in Infants And Children investigation, as well as our own internal processes for a serious incident investigation," a spokesperson said.
More than £5.5m has been raised in memory of teenager Stephen Sutton, the Teenage Cancer Trust has revealed.
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An eight-year-old boy who was diagnosed with tonsillitis died less than 24 hours after being discharged from hospital.