Rob Kardashian made a rare appearance in the public eye when he was featured in his sister Khloe Kardashian‘s 40th birthday post on Instagram.

Of all his siblings, Rob, 37, is especially close to Khloe, who has described herself as a ‘third parent’ to his seven-year-old daughter Dream.

Although he used to be a regular cast member on Keeping Up With The Kardashians, Rob has withdrawn from the limelight in recent years – particularly after the explosive collapse of his relationship with Dream’s mother Blac Chyna.

Now, however, he has featured in a joyous Instagram montage Khloe posted Thursday to celebrate her milestone age.

In footage from a birthday bash, Khloe was presented with a cake as her guests sang Happy Birthday To You with a beaming Rob among them.

Rob Kardashian made a rare appearance in the public eye when he was featured in his sister Khloe Kardashian ‘s 40th birthday video

The birthday girl’s best friend Malika Haqq and grandmother Mary Jo ‘MJ’ Campbell could also be spotted around the festively decorated table.

Khloe’s daughter True, six – whom she shares with her NBA ex Tristan Thompson – is close to Dream’s age and the two children often spend time with one another.

Rob has lately been so shy of public scrutiny that he scarcely even appears on his own Instagram, though he has been known to make an exception for Khloe.

The most recent Instagram picture he posted of himself was a photo of him and Khloe to mark her 39th birthday last June.

‘Wishing you nothing but good health and happiness forever my darling buttercup !’ he wrote to Khloe, who is the sibling closest to him in age.

‘I love you so much and so thankful to have u in my life and for all that U do for Dream and I. I don’t know what I would do without you.’

When Rob turned 37 this March, Khloe posted an Instagram album of them together to wish her ‘baby bobby boy’ the ‘[h]appiest’ birthday.

‘Robert I couldn’t be prouder or more honored to say I am your sister. I couldn’t be prouder to be living life with you,’ she wrote.

Now, he has cheerfully featured in an Instagram montage Khloe posted Thursday to celebrate her milestone age

Of all his siblings, Rob, 37, was always especially close to Khloe, whom he is pictured with back when they were both small children

Khloe has described herself as a ‘third parent’ to his seven-year-old daughter Dream, whom Rob shareswith his former fiancée Blac Chyna

Rob has lately been so shy of public scrutiny that he scarcely even appears on his own Instagram, though he has been known to make an exception for Khloe

The most recent Instagram picture he posted of himself was a photo of him and Khloe to mark her 39th birthday last June (pictured)

‘I couldn’t be luckier that I get to call you whenever I want about absolutely nothing. And the coolest part is, you actually answer the phone for me ha! I thank God every day for our relationship and the relationship that our children get to have.’

Chyna, a former stripper whose real name is Angela Renee White, carried on a seething feud with the Kardashian-Jenner family after her split from Rob.

She unsuccessfully sued multiple members of the family – including Khloe – claiming they connived to have her reality show Rob And Chyna canceled.

After losing the suit, Chyna became a born-again Christian and overhauled her life, quitting OnlyFans, having her plastic surgery reversed and going on the wagon.

On an episode of The Kardashians last year, Khloe described herself as Dream’s ‘third parent’ and confessed that she was not in touch with Chyna.

‘I do not have a relationship with Dream’s mom,’ she said. ‘It’s hard to have a relationship with someone when they sue you for hundreds of millions of dollars.’