A study commissioned by the coffee chain recently found almost half (48 per cent) of people would use a reusable cup to avoid the charge.
In the three-month trial, consumers buying hot drinks in takeaway cups in 35 selected London branches of Starbucks - including the City and West End - will have to pay the extra charge from today.
The proceeds from the levy will be donated to environmental charity Hubub, who will use it to fund further research.
Starbucks' vice president of communications Simon Redfern told the Standard: “We’re hoping that this charge will remind customers to rethink their use of single-use plastic-lined cups, as it has with plastic bags.
"We’ve offered a reusable cup discount for 20 years, with only 1.8 per cent of customers currently taking up this offer, so we’re really interested in working with Hubbub to see how this charge could help to change behaviour and help to reduce waste.”
Gavin Ellis, the co-founder of Hubbub said: “Our early conversations with customers have shown an increased awareness of the need to reduce waste from single-use cups.
"Previous studies have shown that adding a charge on single-use cups is more effective than money off a reusable cup.
"We’re excited to be working on this initiative with Starbucks to find out if this is the case on the high street and to discover what else will encourage people to use reusable cups.”
