Supplies of the morning-after pill could be posted to women following a telephone consultation with a nurse.
London women will be able to stock up on the pill, which they can use “when things don’t go according to plan”.
The service has been launched by the British Pregnancy Advisory Service (BPAS). The pill would be requested by telephone, and delivered without charge to their door.
Also included in the Just in Case kit are condoms, the charity said, to help prevent unwanted pregnancy over the summer.
The morning-after pill works best if it is taken within 12 hours of having unprotected sex. However, it can be taken for up to three days (72 hours) after intercourse.
A spokeswoman from the BPAS said the kit would be delivered to women after speaking with a nurse.
She said that, as the Olympics are set to cause “significant disruption” in London, this could make swift access to healthcare services more difficult if regular contraception fails.
Lead contraception nurse at BPAS, Tracey Forsyth, said: “Our Just in Case kit means you have a back-up there when you need it, wherever you happen to be.
“The sooner you take emergency contraception the more effective it is.
“If you carry an umbrella in your bag or a spare tyre in your boot no-one would suggest you are hoping for rain or planning on a puncture. Having the morning-after-pill to hand is no different. It doesn’t mean you’re planning on taking chances, it means you’re planning on protecting yourself when things don’t go according to plan.”