Olivia Rodrigo is 21! Pop star celebrates her ‘last day of being able to underage drink’ at birthday bash with Tate McRae, Laroi, and Iris Apatow

Olivia Rodrigo threw herself a star-studded birthday party in the hours before she officially turned 21 and became a legal adult in the United States on Tuesday.

The self-proclaimed ‘Spicy Pisces’ – who has 70.1 million followers on social media – endorsed her Instagram slideshow: ‘Today is the last day I can (hypothetically) have underage drinking!’

Olivia made quite the sideshow at the party as she was scantily clad in a panty-flashing halterneck LBD and matching heels

Rodrigo wore her brunette mane in a loose updo and she rocked a vampy shade on her lips.

The three-time Grammy winner made sure to invite her closest friends – Unstable actress Iris Apatow and The Brothers Sun actress Madison Hu – both of whom appeared in her music videos for Bad Idea Right and SOUR Prom.

Olivia Rodrigo (R) threw herself a star-studded birthday party in the hours before she officially turned 21 and became a legal adult in the United States on Tuesday

The self-proclaimed 'Spicy Pisces' - who has 70.1 million social media followers - captioned her Instagram slideshow:

The self-proclaimed ‘Spicy Pisces’ – who has 70.1 million social media followers – captioned her Instagram slideshow: “Today is my last day of (hypothetically) underage drinking!”

Olivia’s other partygoers included Conan Gray, Tate McRae, Laroi and FINNEAS.

Rodrigo – who will soon be releasing a limited-edition cookie with Crumbl – ate a cookie with an image of himself as a child on it.

The Can’t Catch Me Now singer offered up no fewer than three birthday cakes at her soirée – including a ‘vegetarian’ funfetti cake – which had been bizarrely cut into small slices.

Strangely missing from the festivities was Olivia’s boyfriend since October – Argylle actor Louis Partridge – who posted two Instagram photos of himself enjoying Disneyland on Monday.

And even though there was no sign of Rodrigo, she easily could have took the photos of the 20-year-old Englishman enjoying the ‘happiest place on earth.’

The Cali-born pop star previously ended her six-month affair with DJ/producer Zack Bia in August 2022 following her seven-month relationship with Proof of Love producer Adam Faze in February 2022.

And Olivia’s famous 2021 hit Drivers License is said to have been inspired by her love triangle with High School Musical: The Musical – The Series lead Joshua Bassett and Sabrina Carpenter.

Rodrigo is enjoying the last moments of free time before embarking on her 77-date Guts World Tour in support of her second studio album this Friday at the Acrisure Arena in Thousand Palms, CA.

The half-Filipino beauty will next be nominated for two trophies – International Artist of the Year and Best International Song – at the 2024 Brit Awards, airing March 2 on ITV/ITVX/YouTube.

Olivia – who gets 59.4 million monthly listeners on Spotify – has been nominated for six trophies, including Song of the Year, at the 2024 iHeartRadio Music Awards, airing April 1 on Fox.

Olivia made quite the sideshow at the party as she was scantily clad in a panty-flashing halterneck LBD and matching heels

Olivia made quite the sideshow at the party as she was scantily clad in a panty-flashing halterneck LBD and matching heels

Rodrigo wore her brunette mane in a loose updo and she rocked a vampy shade on her lips

Rodrigo wore her brunette mane in a loose updo and she rocked a vampy shade on her lips

The three-time Grammy winner made sure to invite her closest friends - Unstable actress Iris Apatow (L) and The Brothers Sun actress Madison Hu (R) - who both appeared in her music videos for Bad Idea Right and SOUR Prom

The three-time Grammy winner made sure to invite her closest friends – Unstable actress Iris Apatow (L) and The Brothers Sun actress Madison Hu (R) – who both appeared in her music videos for Bad Idea Right and SOUR Prom

Olivia's other partygoers were Conan Gray (2-L), Tate McRae (2-R), Laroi (R) and FINNEAS

Olivia’s other partygoers were Conan Gray (2-L), Tate McRae (2-R), Laroi (R) and FINNEAS

Rodrigo – who will soon be releasing a limited edition cookie with Crumbl – ate a cookie with an image of himself as a child on it

Rodrigo – who will soon be releasing a limited edition cookie with Crumbl – ate a cookie with an image of himself as a child on it

The Can't Catch Me Now singer offered up no fewer than three birthday cakes at her soirée - including a 'vegetarian' funfetti cake - which was bizarrely cut into small slices

The Can’t Catch Me Now singer offered up no fewer than three birthday cakes at her soirée – including a ‘vegetarian’ funfetti cake – which was bizarrely cut into small slices

Strangely missing from the festivities was Olivia's boyfriend since October - Argylle actor Louis Partridge - who on Monday posted two Instagram photos of himself enjoying Disneyland

Strangely missing from the festivities was Olivia’s boyfriend since October – Argylle actor Louis Partridge – who on Monday posted two Instagram photos of himself enjoying Disneyland

And although there was no sign of Rodrigo in sight, she could easily have captured the photos of the 20-year-old Englishman enjoying the 'happiest place on earth'

And although there was no sign of Rodrigo, she could easily have captured the photos of the 20-year-old Englishman enjoying the ‘happiest place on earth’

The Cali-born pop star (pictured February 4) enjoys her final moments of rest before embarking on her 77-date Guts World Tour in support of her second studio album this Friday at the Acrisure Arena in Thousand Palms, CA

The Cali-born pop star (pictured February 4) enjoys her final moments of rest before embarking on her 77-date Guts World Tour in support of her second studio album this Friday at the Acrisure Arena in Thousand Palms, CA