The long wait for fiber optic broadband in the city of Boston is finally over.

In a surprise announcement with Boston Mayor Martin J. Walsh and Verizon officials, Verizon announced it will commit to at least $300 million in investments over the next six years to bring fiber to the home service to residents of the metro area.

Construction of the fiber-optic network will be completed on a neighborhood-by-neighborhood basis according to customer demand. Initially, the project will begin in Dorchester, West Roxbury and the Dudley Square neighborhood of Roxbury in 2016, followed by Hyde Park, Mattapan, and other areas of Roxbury and Jamaica Plain. The city has also agreed to provide an expedited permitting process to encourage the project.

“Boston is moving faster than our current infrastructure can support, and a modern fiber-optic communications platform will make us a next-level city,” Walsh said in a statement.

“This transformation isn’t just about advanced new fiber-optic technology — it’s about the innovative services this platform will allow people to create and use, today and in the future,” Verizon Wireline Network president Bob Mudge said in a statement.

Bringing FiOS inside the city of Boston will challenge the de facto monopoly Comcast had held for years. The only alternative most residents have is Verizon DSL.

The dramatic turnaround came six months after Verizon adamantly told the Boston City Council Verizon FiOS expansion was dead. Verizon announced it would stop FiOS expansion in 2010 to concentrate on its existing FiOS commitments and better marketing the service to attract more customers.

The sudden end to FiOS expansion six years ago caught many cities by surprise. As a result, in several areas, the fiber service is only available in select suburbs and not city centers.

Verizon’s unions have also pushed for further FiOS expansion, but today’s announcement is expected to have no impact on plans by the Communications Workers of America and the International Brotherhood of Electrical Workers to strike Verizon starting early Wednesday morning.

The partnership also covers Verizon Wireless and its plans to attach wireless equipment to city street lights and utility poles without a lengthy permitting process.

Verizon was also likely offered a much easier time securing a license to offer cable television service, a stumbling block Verizon has experienced in several large cities.

Echoing Google Fiber, Verizon will try to win itself some free marketing and buzz by giving residents a chance to compete to see what neighborhoods get FiOS first. A free online registration process will be used to assess demand and help Verizon prioritize its fiber-optic network construction schedule.

Verizon will also support digital initiatives for the income-challenged, including a $100,000 Digital Equity contribution to the city, offered to support a mobile hotspot lending program at the Boston Public Library enabling Internet access to families on an as-needed basis.

Boston neighborhoods marked “A” will be upgraded to FiOS first, followed by “B” and so on. The upgrade effort is expected to take at least six years.