Treasure Island Hotel and Casino (also known as Treasure Island Las Vegas and "TI") is a pirate-themed hotel and casino located on the Las Vegas Strip in Paradise, Nevada, U.S. It includes 2,885 rooms and a 47,927 sq ft (4,452.6 m) casino. The resort is owned and operated by businessman Phil Ruffin.

Treasure Island was developed by casino owner Steve Wynn through his company, Mirage Resorts. Project designers included Joel Bergman and Jon Jerde. Wynn announced Treasure Island in October 1991, and construction began four months later. The resort opened on October 26, 1993. Treasure Island was among several family-oriented resorts to open in Las Vegas during the 1990s, taking advantage of the growing tourist demographic. Treasure Island's facade was built with a lagoon containing two pirate ships. Free pirate battles were performed daily for spectators over the next two decades. The resort has also hosted Mystère since 1993, making it the longest-running show by Cirque du Soleil.

In 2000, MGM Grand Inc. acquired Mirage Resorts and was renamed MGM Mirage. Treasure Island's pirate theme was scaled back during a 2003 project aimed at attracting a more mature audience, in contrast to the family trend of the 1990s. MGM's revamp included new signage abbreviating the resort's name as "TI", while the original pirate show, Battle of Buccaneer Bay, was replaced by Sirens of TI.

MGM struggled financially during the Great Recession. In 2009, it sold Treasure Island to Ruffin for $755 million. Ruffin targeted a middle-class clientele, making various changes to appeal to the demographic. He added two signature restaurants: Gilley's Saloon in 2010, and Señor Frog's in 2012. The pirate shows ended the following year, although the ships remain on display.

In 1986, casino owner Steve Wynn purchased property on the Las Vegas Strip extending north to Spring Mountain Road. He opened a resort, The Mirage, on the southern portion of the land in 1989. Wynn had always wanted to build a second casino on the remaining acreage, which was being used as a parking lot for the Mirage.

Wynn's company, Mirage Resorts, announced the Treasure Island project on October 30, 1991. Like other new resorts in Las Vegas, Treasure Island was planned as a family-oriented property, taking advantage of the growing tourist demographic. It would also cater to a middle-class clientele, unlike the Mirage. Groundbreaking took place on March 2, 1992, earlier than anticipated. Construction was originally expected to cost $300 million, but the final cost rose to $430 million.

Employees and their families stayed at Treasure Island a couple days before the opening to put the resort through a trial run. Treasure Island opened to the public at 10:00 p.m. on October 26, 1993, following a private opening for VIPs, including Nevada governor Bob Miller. The resort's facade featured a free pirate show taking place in a man-made lagoon. Wynn's other Strip resort, the shuttered Dunes, was imploded the following night in a grand ceremony which incorporated the pirate show. One of the ships fired its cannon as the implosion began, simulating the resort's destruction by cannonballs.

In 1996, Treasure Island hosted a naturalization ceremony for 93 workers. It was the first Las Vegas resort to hold such an event.

A man robbed the casino twice in 2000, stealing more than $30,000. He was arrested after a failed third attempt, during which he shot a security guard. He was sentenced to 130 years in prison.

The Prairie Island Indian Community, owners of a Treasure Island casino resort in Minnesota, filed a $250 million damages lawsuit against Mirage Resorts in May 2000. The suit alleged that Wynn violated trademark law by using the "Treasure Island" name for his own casino resort. The suit also requested that Wynn be barred from using the name, which Wynn said he registered in 1993.

Wynn departed Mirage Resorts in 2000, when it was acquired by MGM Grand Inc., later renamed MGM Mirage.

Treasure Island's family amenities included the pirate show and an arcade. However, the pirate theme and family appeal would be gradually scaled back in subsequent years. In April 2003, Treasure Island announced a major revamp to transform the resort into a more sophisticated property aimed primarily at adults, although children would still be welcomed. Describing the resort's transformation, Treasure Island president Scott Sibella said, "We've seen a return of Las Vegas to its roots as an adult destination. As the city has evolved, so too has Treasure Island." He said, "We've evolved from a yo-ho-ho feel to a more sophisticated feel. We want to change the exterior to introduce the outside to what we've already done inside." As part of the revamp, Treasure Island began using the abbreviated name "TI". Sibella described the new name as trendy and sexy, and said it was a name that residents and guests already used. He compared the abbreviated name to the former Desert Inn resort, also known as "D.I." MGM Mirage began a marketing campaign for TI in June 2003, including advertisements in various publications.

MGM struggled financially during the Great Recession, and businessman Phil Ruffin made an offer to buy Treasure Island. MGM accepted and announced the deal at the end of 2008. The purchase was finalized on March 20, 2009, at a cost of $755 million. At the time, Treasure Island was the only hotel-casino on the Strip to be owned by a single individual, as others are corporate-owned. Because of the sale, Treasure Island was removed from MGM's extensive customer database. Later that year, the resort joined K Hotels, a worldwide collection of approximately 50 hotels. Amid the recession, Ruffin spent $20 million on various changes to target a middle-class clientele. The hotel rooms were left untouched, as MGM had conducted a $92 million renovation of them shortly before selling the resort to Ruffin.

A rooftop swamp cooler caught fire in July 2012, sending smoke through hallways of the upper hotel floors, which were evacuated. The fire caused $20,000 in damage, but resulted in only minor injuries for guests.

Ruffin is a business partner of Donald Trump's and a supporter of his presidential campaign. Trump has held several campaign rallies at Treasure Island, including one in 2016 during which an audience member attempted to assassinate him.

In 2019, Treasure Island's hotel joined Radisson Hotel Group. Under the agreement, the resort kept its name and exterior signage. Room renovations began that year. State casinos were temporarily closed in 2020, due to the COVID-19 pandemic in Nevada, and the closure allowed planned renovations across the resort to accelerate. Among the additions was an expanded sportsbook.

Treasure Island includes a 47,927 sq ft (4,452.6 m) casino, and has 2,885 rooms, located in a 36-story tower. As part of the 2003 transformation, the tower was given a darker paint color, using 6,200 gallons of terra cotta/"Salmon Stream" paint, replacing an earlier pink coloring. Treasure Island received a Four Diamond Award every year from 1999 to 2013.

Tangerine, a nightclub featuring an orange and white interior, operated from 2004 to 2007. Fashion designer Christian Audigier opened an eponymous nightclub at Treasure Island in 2008, in partnership with Pure Management Group. The decor included rhinestone-encrusted skulls and two large tanks containing jellyfish. Audigier said, "When you're going into a club, you want to see sparkling and glitter and rhinestones". Christian Audigier did not perform as well as Ruffin would have liked, prompting its closure in 2010. Ruffin's other changes included a $3 million makeover of the spa, with renovations overseen by his wife Oleksandra Nikolayenko. At one point, Treasure Island had 18,000 sq ft (1,700 m) of convention space, which received a $4 million renovation in 2012. Four years later, the space was expanded to 30,500 sq ft (2,830 m).

In 2013, the resort announced plans to build a three-story mall, replacing the northern portion of the pirate lagoon area. It was completed two years later, and includes a CVS Pharmacy on the first floor. At the end of 2015, the resort announced that it would lease the upper floors to Victory Hill Exhibitions. In 2016, the company opened the Avengers S.T.A.T.I.O.N., an interactive self-guided exhibit based on the Marvel Cinematic Universe.

The Mirage-Treasure Island Tram traveled between the two resorts. It ceased operations in June 2024 prior to The Mirage's closing on July 17, 2024.

Various themes were considered for the resort, until a friend of Wynn's suggested the name "Treasure Island", resulting in a pirate theme. It is named after the 1880s novel Treasure Island by Robert Louis Stevenson. The resort was designed by Joel Bergman, who previously designed the Mirage. Bergman designed the Treasure Island tower with a floorplan that branched out three ways in a Y-shape, with elevators in the center. This was done for convenience to guests, making the walk to their rooms brief. The Y-shape was modeled after the Mirage hotel tower.

Wynn's Atlandia Design worked with Jon Jerde and Olio Design to create the pirate village and lagoon area, originally known as Buccaneer Bay, and later as Siren's Cove. During the design phase, the hotel's lobby entrance was moved to the resort's south side, in order to maintain Buccaneer Bay's location on the east side along the Strip. Jerde's assistants traveled across Europe, India and Nepal searching for historic objects such as doors and columns, which were then replicated for Buccaneer Bay. The lagoon is 65 feet deep, and originally contained 2 million gallons of water. It uses wastewater recycled from a water treatment plant located beneath the resort's parking garage. A maintenance team, including divers, works to keep the lagoon clean.