The move is part of almost £2 million funding aimed at boosting struggling town centres.
Falkirk Council will receive £1,976,000 from the Scottish Government’s Town Centre Fund which must be spent by March 2020.
A meeting of the council’s executive agreed that the money will help several projects make the three town centres more “vibrant, enterprising and accessible”.
Falkirk town centre will also get luggage lockers to support tourism and the council has pledged to work with Scotrail/Abellio to look at improving accessibility and connections to both of the town’s railway stations.
Other projects in the pipeline include improvements to Newmarket Street and Lint Riggs.
In addition to the free WiFi, Grangemouth’s cash will be used to progress the ‘Making Places’ project to improve the town centre while the council will work with local land owners to agree demolition of long-standing vacant buildings.
Bo’ness’ cash will be used to improve access and change the layout of the library.
Falkirk Delivers manager Alex Fleming said getting WiFi was “very positive” step for the town centre.
She said: “It’s a fantastic benefit because it will help Falkirk become a digital town. That’s not just about people coming into the town being able to use WiFi, it will also allow us to deliver digital training to our businesses and allow them to compete a bit more with online shopping.
“It’s a very positive move.”