Previously there has been no register for retailers and those aged 16 and over were able to buy tobacco products.
Retailers breaking the law risk a Â£5,000 fine or one month in prison.
Conseiller Diane Baker, the Medical Committee chairwoman, said the new rules made controls clearer for everyone.
She said: "We're all fully aware of the dangers and we don't want to see the youngsters even starting to smoke."
In regards to introducing plain packaging for cigarettes Mrs Baker said it was likely the committee would suggest following Guernsey's lead on any moves.
Sark law defines tobacco products as tobacco or products containing tobacco, smoking mixtures intended as a substitute for tobacco and cigarette paper.
The law comes into force on 1 February, although there is a two-month delay in enforcing the licensing element to allow existing retailers to obtain licences.
The legal age for buying tobacco in Sark has been raised to 18 under new rules that also require retailers to be licensed.