He played for the Mapuá Institute of Technology Cardinals in the NCAA from 1983 to 1986. He entered the PBA in 1988 as part of the illustrious quartet alongside 1988 Rookie of the Year Jojo Lastimosa, many-time Mythical Team and Best Defensive Team Member Jerry Codiñera and perennial Best Defensive Team Member Glenn Capacio.
He first played for Hope in the PABL (now known as the PBL). then he transferred to YCO and again to Swift wherein he give the franchise a championship before going to the pros but Swift delayed his pro debut because of some conflicts.
He played his entire career with the Purefoods TJ Hotdogs and won several championships, mostly in the PBA All Filipino Cup; he also played for the Philippine national team including the 1998 Philippine Centennial team.
Patrimonio holds several PBA records including most consecutive games played (596) and most PBA Most Valuable Player awards (4 tied with Ramon Fernandez). He was also the second player after Bogs Adornado to win back-to-back MVP awards in 1993-1994 and also the second player to win three Best Player of the Conference award after Vergel Meneses. He also shares the distinction of having played the most Asian Games (4) with 1990 PBA MVP Allan Caidic.
During his playing years in the PBA, Alvin found time to do movies. He first appeared as guest in the Mars Ravelo classic Bondying which starred Jimmy Santos. Then he was launched together with Jerry Codinera and Bong Alvarez in the film Last Two Minutes in 1990. The movie was a top-grosser at the box-office and spawned a sitcom of the same title aired over PTV-4. The Captain was also paired with Maricel Soriano in the remake of the Robert Jaworski/Nora Aunor film Dobol Dribol in 1992 and did Tasya Fantasya opposite Kris Aquino in 1994.
In 2004, 16 years after playing in the pro league, Patrimonio announced his retirement to concentrate more on his duties as the current team manager of the Purefoods franchise in the PBA. The best power forward in the annals of the PBA, he redefined the meaning of power forward as a prolific and phenomenal scorer ending his career as the league’s No. 3 scorer with 15,091 just behind all-time greats Ramon Fernandez and Abet Guidaben with 18,996 and 15,775, respectively.
On November 26 2005, he played in the Legends 3-Point Shootout during the PBA All-Star in Laoag City, Ilocos Norte. The game saw Patrimonio sink the very last money ball to prop the Legends, also composed of Ronnie Magsanoc and Frankie Lim, to a 41-39 win over the young Turks of Jimmy Alapag, Ren-Ren Ritualo and Dondon Hontiveros.
Alvin stands at 6'3 and plays the power forward position but during his amateur days he's a combo big man because he can also play the center position with ease. his style of play is somewhat comparable to Karl Malone because they're not only strong players but a big man who has a decent outside touch. he also has a reputation for being one of the most beloved players in philippine basketball and the second most popular player behind Robert Jaworski because of his love for his fans and he entertains every fan that wants his autographs no matter how many they are and even when the coliseum is already closing he will continue signing specially when he sees his special friends Sharif Benito and Gertrude Bote. He is also called "Captain Lionheart" because of his leadership qualities and showing the heart of a true champion every game which resulted in many memorable game-winning performance in his name. He is somewhat called "a complete package" wherein aside from being a talented basketball player he also has the looks that girls go ga-ga over him. Apart from being a basketball player, he also is an endorser of many products such as Purefoods, Swatch, Lipovitan, Kaypee Shoes (during his first few years as a pro player), Nike Philippines, etc. he also appeared in a political ad campaign for Senator Manny Villar. In 1991, he signed a 5-year 25 million peso contract and begin the era of the multi-millionaire players.
This family not only loves sports, they also love animals. They have 6 chihuahuas, 1 German shepherd, 1 Labrador & a Siberian Husky. They also have a fish pond wth Japanese Koi and a turtle. As you enter their house in the foyer are African love birds chirping to welcome you. They also had a parrot but unfortunately he died. His name was T-BIRD. They also had a pet dinosaur. His name was T-REX