Arjun posted a picture on Instagram. The photograph features the two brothers twinning in ivory coloured sherwanis as they posed for the camera.
"Many many happy returns of the day to my sweetest brother who is my biggest moral support . Wish you a wonderful day and a lovely year to come. @allusirish," Arjun wrote as the caption.
Sirish, who turned 34 on Sunday, went on to thank his brother for the note.
He wrote: aceThank you Bunny! Love you!!!"
Talking about Arjun's upcoming slate of work, he will be seen in Pushpa.
Based on true events, Pushpa revolves around the red sanders heist in the hills of Andhra Pradesh. With this film, the audience will see Allu Arjun and Rashmika Mandanna, sharing screen space for the first time.
The film is directed by Sukumar, with sound by Oscar-winner Resul Pookutty. It is slated to release on August 13.