Katz unveiled his "Spray Paint Action Plan" on Tuesday, saying it will be presented to city council shortly.
Katz, who was elected mayor in a 2004 byelection, is seeking his first full mandate in the Oct. 25 civic election.
In addition to prohibiting the sale of spray paint to anyone under the age of 18, Katz's plan would also to prohibit the possession of spray paint in public areas by anyone under 18 years.
It would also require stores that carry spray paint to display signs that state selling spray paint to minors is against the law.
Katz said he will raise the city's graffiti removal budget to $641,000 this year, a $200,000 boost, as well as set aside funds for city murals and summer graffiti removal projects.
“Random graffiti is a blight that disgraces any community," Katz said in a release Tuesday.
"Cleaning it up is important but preventing it a far better solution. A proactive spray paint action plan will help keep our neighbourhoods sparkling."
The city of London, Ont., passed a similar bylaw to crack down on graffiti in May, reportedly the first of its kind in Canada. Under the bylaw, retailers who sell "graffiti implements" to minors are subject to fines of up to $5,000.
Katz said anti-graffiti bylaws have worked in New York, Chicago and Los Angeles.