Christie said he is wary of imposing new regulations on small businesses, The Star-Ledger of Newark reported.
"Nonetheless, I sign this bill because of the documented and well-understood risks associated with the misuse of indoor tanning systems," he added in an unusual signing statement. "Use of tanning devices is particularly dangerous for the young, as studies indicate that individuals who begin tanning before age 35 have a 75 percent higher risk of melanoma."
The measure, which also bans those younger than 14 from spray tanning, was inspired by the uproar over Patricia Krentcil of Nutley, who brought her 5-year-old daughter to a tanning salon. Krentcil denied bringing the girl into the tanning bed and a grand jury later refused to indict her but the case became a national sensation.
Christie called the case a "single but breathlessly reported incident."
Under the law, which takes effect in six months, parents will have to accompany 17-year-olds on their first visits to tanning salons.
The industry lobbied against the law, saying it would cut profits. The state already banned anyone under 14 from using tanning beds and required parental consent for those under 18.