Through a channel sharing agreement, the two stations transmit using WPTZ's spectrum from an antenna on Vermont's highest peak, Mount Mansfield.

The station signed on the air on December 8, 1954, as WIRI, originally licensed to the hamlet of North Pole, New York.

The sale protected new Fox affiliate WFFF-TV, which was initially operated by WPTZ under a local marketing agreement (LMA) and shared the analog transmitter on Terry Mountain.

Sunrise then decided to swap WPTZ/WNNE, along with Smith Broadcasting-owned KSBW in Salinas, California, to what was then known as Hearst-Argyle Television in return for WNAC-TV in Providence, Rhode Island, and WDTN in Dayton, Ohio; both of those stations were forced to be divested by Hearst-Argyle due to significant signal overlap with WCVB-TV in Boston and WLWT in Cincinnati (the FCC did not allow common ownership of two stations with overlapping coverage areas until 2000).

WFFF began operating as an independently-owned and controlled station around the same time Hearst took over WPTZ/WNNE when the LMA with WPTZ was terminated.

On June 23, 1999, WPTZ petitioned the FCC to change its community of license (COL) from North Pole to Plattsburgh.

[6] The substitution of WBRE in place of WPTZ lasted until July 19, 2012, when the deal was reached between Hearst and Time Warner.

On June 12, 2018, WPTZ announced it was moving to a brand new broadcast facility in South Burlington, Vermont, in a building that contains both a data center for Keurig Green Mountain and the main offices of Ben & Jerry's.

WPTZ continued to maintain the Television Drive facility for several months in Plattsburgh as a secondary studio, while closing a now-duplicative and smaller bureau in Colchester, Vermont.

[10] WPTZ later relocated the bureau to a new location at 308 Cornelia Street in Plattsburgh, taking over the former Glens Falls National Bank branch and renovating the building to become its new secondary studio in the summer of 2020.

On November 19, 2019, WPTZ, WNNE and CBS affiliate WCAX-TV (channel 3) were knocked off the air by a fire at their combined antenna at the transmitter facility.

The outage affected over-the-air and satellite viewers; cable subscribers continued to receive the three stations via direct fiber feeds,[11][12] while Vidéotron in Quebec temporarily replaced WPTZ with Detroit NBC affiliate WDIV-TV.

This marked the network's first foray into the Plattsburgh and Burlington area along with St. Lawrence County in New York and eastern portions of the adjacent Watertown market where WPTZ has long served as the default NBC affiliate on cable.

[18] In May 2016, Comcast began carrying WPTZ-DT2's high definition feed on digital channel 706 for Burlington (as well as Upper Connecticut River Valley) viewers and Charter began carrying WPTZ-DT2's high definition feed on digital channel 711 for Plattsburgh viewers.

In the 1980s, WPTZ preempted select NBC shows, including NBC News Overnight (due to the station signing off overnight), GO!, Hot Potato, The Match Game-Hollywood Squares Hour, Santa Barbara, Trialwatch, the 1990 version of Let's Make a Deal, and the Bob Goen version of Wheel of Fortune.

In order to cover that state, from the mid-1990s to July 2019,[10] WPTZ operated secondary facilities known as the Vermont Bureau on Roosevelt Highway (US 2/US 7) in Colchester.

In addition to the Upper Valley and Vermont bureaus, WPTZ airs national news from Hearst Television's Washington, D.C. bureau.

With the departure of Thom Hallock (whose contract was not renewed by station) on November 23, 2007, WPTZ was left with an all-woman weeknight anchor team.

In August 2018, WPTZ's Upper Valley bureau moved from White River Junction to a new space on Mechanic Street in Lebanon, New Hampshire.

[10] To coincide with the aforementioned relocation to the new South Burlington facilities, WPTZ became the last station in the market to broadcast newscasts in high definition.

Both WPTZ and WSTM-TV lost those statuses on December 1, 2016, when WVNC-LD signed on as the Watertown market's first full-time NBC affiliate.

[28] Like the other network stations that serve Plattsburgh and Burlington, WPTZ has a large audience in southern Quebec, Canada.

This includes Montreal, a city with ten times as many people as all of WPTZ's entire American viewing area.

For many years, station promos and IDs have read "North Pole–Plattsburgh–Burlington–Montreal" or "Plattsburgh–Burlington–Montreal" to acknowledge its large cable viewership in Canada.