John Arrillaga Sr., the real estate developer who physically transformed Silicon Valley into tech office parks from orchards and became a major donor to Stanford University, died on Monday in Portola Valley, Calif. He was 84.

His daughter, Laura Arrillaga-Andreessen, announced his death in a post on Medium. His family declined to cite the cause.

Starting in the 1960s, Mr. Arrillaga developed Silicon Valley’s bucolic farmland into a sprawling network of corporate campuses. At the time, the semiconductor industry was taking off in the Santa Clara Valley, with companies like Intel growing as quickly as they could find buildings to expand into.

To meet that demand, Mr. Arrillaga and his business partner, Richard Peery, bought up thousands of acres of farmland around California towns including Mountain View, Sunnyvale and San Jose. Even before they secured tenants, they created developments of low-slung concrete buildings that were cheap and easy to build.

They ultimately constructed more than 20 million square feet of commercial real estate. Many of those developments housed tech companies, among them Intel, Apple, Hewlett-Packard and Google.

Mr. Arrillaga and Mr. Peery became billionaires as the value of the properties soared. Forbes pegged Mr. Arrillaga’s net worth at $2.5 billion.

As the tech industry grew and Silicon Valley’s population multiplied, some residents began voicing opposition to development. Several of Mr. Arrillaga’s projects ran into obstacles: Residents protested the height of proposed 100-foot office towers in Palo Alto and disagreed with the location of a new library in Menlo Park.

Later in life, Mr. Arrillaga also physically transformed Stanford, which he had attended on a basketball scholarship. He donated money for over 200 projects and buildings at the university, including at least nine buildings and rooms bearing his family’s name and 57 scholarships. In 2013, he pledged $151 million to the university, the largest gift to Stanford from a single living donor.

Mr. Arrillaga was born on April 3, 1937, in Inglewood, Calif. His father, Gabriel, was a professional soccer player who later became a laborer in a Los Angeles produce market. His mother, Freda, was a nurse.

In 1955, Mr. Arrillaga enrolled at Stanford, where he studied geography. At 6 feet 4 inches tall, he captained the basketball team while juggling jobs to cover his expenses.

After graduating in 1960, he briefly played professional basketball — according to an article in Fortune, he was on the roster of the San Francisco Warriors for six weeks, although there is no record of his having gotten into a game — before going into commercial real estate.

In 1966, he and Mr. Peery started the real estate firm Peery Arrillaga. Their partnership lasted five decades. In 2006, they sold around half of their 12 million-square-foot portfolio for $1.1 billion to a real estate investment division of Deutsche Bank.

In 1968, Mr. Arrillaga married Frances Marion Cook, a sixth grade teacher and fellow Stanford graduate. They had two children. She died of lung cancer in 1995. In 2003, he married Gioia Fasi, a former lawyer from Honolulu.

She and his daughter survive him, as do his son, John Jr.; two sisters, Alice Arrillaga Kalomas and Mary Arrillaga Danna; a brother, William Arrillaga; and four grandsons.

Mr. Arrillaga’s ties to the tech industry became even closer in 2006 when his daughter, who is a lecturer at the Stanford Graduate School of Business, married Marc Andreessen, a venture capitalist and a founder of Netscape.

Mr. Arrillaga began making small donations to Stanford just after graduating. By the early 2000s, his donations to the school, primarily to its athletics department, had soared to over $80 million. In 2006, he gave $100 million to Stanford, which was the largest sum by a single donor until he eclipsed that with his 2013 donation.

For 30 years, Mr. Arrillaga rebuilt and gave money to nearly all of Stanford’s athletic facilities, including Maples Pavilion in 2004 and Stanford Stadium in 2005 and 2006. The Arrillaga name is so ubiquitous on campus, found on the Frances C. Arrillaga Alumni Center, the Arrillaga Family Dining Commons and both campus gyms — that students nicknamed the gyms “Nearrillaga” and “Farrillaga” to tell them apart.

Mr. Arrillaga, who avoided media coverage and shunned interviews, developed a reputation for attention to detail in his construction projects.

While rebuilding Stanford’s football stadium, “he selected every single palm tree, worked out the best form for every structural element and created his own designs for the seating,” Ms. Arrillaga-Andreessen wrote in her Medium post. She added that he was known for “personally picking up every single piece of trash he saw and rearranging single stones in fountains across the campus.”