A rare 186-acre West Tisbury property owned by the son of former Washington Post publisher Katharine Graham was sold Friday to two adjacent property owners for $32.5 million, a record sale for a single real estate transaction on the Island.

West Tisbury Holdings Realty Trust, a partnership of the families of Brian L. Roberts and Dirk Ziff, acquired the sweeping property near Lambert’s Cove on the Island’s north shore from the estate of William W. Graham, according to Edgartown attorney Ronald Rappaport, who represented the purchasers. Mr. Graham, a Los Angeles lawyer and investor who had enlarged, restored and carefully preserved the land, died in December 2017.

“As longtime owners of abutting properties, they appreciate the beauty and historical significance of this part of the Vineyard,” Mr. Rappaport said of Mr. Roberts and Mr. Ziff. “The prior owners have been excellent stewards of the property and the new owners intend to follow in their footsteps.”

Mr. Roberts is the CEO of Comcast and Mr. Ziff, whose grandfather co-founded Ziff Davis Publishing, is managing director of Ziff Capital Markets. Both have owned homes west of the Graham estate for a number of years and share the same access road. In 2016, Mr. Ziff expanded his holdings, buying a bordering 7.6-acre property from his younger brother Daniel for $28 million. That sale, although between family members, marked the highest price recorded to date for a single property on the Vineyard. A handful of other properties, mostly in Edgartown, have sold for more than $20 million in recent years.

The Graham property was part of a larger estate, 217 acres of which was acquired by Mrs. Graham in 1972 for $1.46 million at the urging of Gazette editor Henry Beetle Hough, who was worried that it might fall into the hands of developers. Over three decades until her death in 2001, her Island home — known as Mohu — was a gathering spot for heads of state, literary figures and other luminaries.

The house at Mohu was later disassembled and her son focused on tending the land, which includes diverse habitats of shore, wetlands, morainal forest and meadow, and painstakingly maintained its network of roads, trails and landscapes.

Following Mr. Graham’s death, the property went on the market in August with an asking price of $39.5 million. Much of the land remains undeveloped, but includes his five-bedroom home, a one-bedroom cottage fronting Lambert’s Cove Beach, a barn and caretaker’s home. The sale does not include a 50-acre parcel where Mohu once stood, which remains in the Graham family.

Mr. Rappaport said the new owners do not intend to develop the property. “The intention is to keep all existing structures as part of the property with the possible exception of Bill Graham’s house and the small beach house,” he said.

Tom LeClair and Gerret Conover of LandVest Martha’s Vineyard were the exclusive brokers for the sale of the property on behalf of two trustees who are administering a portion of Mr. Graham’s estate. Proceeds from the sale will go to two beneficiaries of the trust — both are charities that have not been named.

“It’s an incredible piece of the Island,” Mr. LeClair said at the time it was listed. “Certainly, one of the most important pieces of property because of its size, [and] historically it’s been so very important.”

The 186 acres and buildings were assessed at $35.3 million by the town of West Tisbury this year, with a property tax estimated at $213,912.