Diddy and girlfriend Cassie Ventura celebrate his one-time protege Usher's birthday in his 'n' hers leather

He mentored Usher at the beginning of his career and they’ve remained good friends. 
So of course Diddy was on hand to celebrate his former protégé’s 35th birthday in Los Angeles on Monday. 

The 43-year-old music mogul brought his girlfriend Cassie Ventura to the bash at West Hollywood’s Bootsy Bellows nightclub and the couple dressed up for the occasion in matching leather.

Matching: Diddy and his girlfriend Cassie Ventura chose matching leather looks to celebrate Usher's 35th birthday in LA on Monday night

Diddy chose a leather top which he paired with black trousers and despite the late hour, a pair of sunglasses. 
Cassie paired a loose white V-neck sweater with baggy black leather pants and black stilettos.  
She carried a large black handbag and left her signature half-shaved hair loose around her shoulders.

Shady! It may have been nighttime but that didn't stop Diddy from donning a pair of sunglasses as he left Booty Bellows in West Hollywood

Casual: While Cassie's white sweater and baggy leather pants were decidedly casual, she spiced up her outfit with heels and a hint of cleavage

Although her baggy outfit hid Cassie’s figure, the deep V-neck of her sweater showed off a hint of cleavage. 

Before the duo arrived at Bootsy Bellows, the popular hotspot owned by David Arquette, John Terzian, and Brian Toll, they first enjoyed a romantic meal together at Hakkasan in Beverly Hills.

Confirmed: Cassie (seen here with a mutual friend) and Diddy have been rumoured to be dating since 2011 but it wasn't until August last year that the Revolt TV creator confirmed his relationship status

However, during an October 4 interview on The View, Diddy made it clear that he doesn't plan to wed, saying: 'I think a lot of people too much on marriage and not enough on happiness.' 
'It definitely would be a dream come true for me to just one day be ready for that. 
'I'm not really looking because I know the responsibility that comes with that and I think a lot of people, they jump into that and they're not honest with themselves.

Stylish: Cassie arrived at Hakkasan in Beverly Hills in this chic coat which she later ditched to go clubbing

Upon their arrival Cassie was sporting a jacket with leather sleeves which she later ditched for their night of clubbing. 
The twosome have been rumoured to be dating since 2011 but it wasn't until August last year that the Revolt TV creator confirmed his relationship status via Instagram.
'I don't want to get married and not make that woman be the best.'
While Usher and Diddy have remained close, the Voice coach previously revealed the older rapper was not the best influence on him when he was just starting out.

Party time: Diddy left Hakkasan after a romantic meal with Cassie to celebrate Usher's birthday party at Bootsy Bellows

Travelling in style: Cassie jumped into Diddy's car following their romantic meal

Speaking about Diddy, who used to be known as Puff Daddy, he said: ‘I was introduced to everything by Puff Daddy when I was only 15 - parties, women, sex and drugs.’
‘I've had a taste of it but I'd never let it take me over.’
He later added: ‘I had Puff as my mentor, but I wouldn’t pass on any of the advice he gave me.
Diddy wasn’t the only celebrity who attended Usher’s birthday bash at the popular celebrity haunt. 

Pretty Little Liars actress Ashley Benson was on hand to celebrate with her boyfriend Ryan Good.

LBDs: Pretty Little Liars actress Ashley Benson and Basketball Wives LA star, Draya Michele donned little black dresses for the occasion

She showed off her toned pins in a short black dress and ankle boots while Ryan was casual in jeans, a T-shirt and a leather jacket. 
Basketball Wives LA star, Draya Michele also kept up the leather theme in a skintight dress while Justin Bieber’s manager Scooter Braun tweeted: ‘great night out for my brother @usher's birthday. #GreatParty’

Celebrate: Ashley brought her boyfriend Ryan Good to the club to celebrate Usher's birthday