Nitin – who has appeared in films such as Bride and Prejudice and Charlie and the Chocolate Factory – will play Mr Masood, husband to Zainab (Nina Wadia). Himesh, meanwhile, is to appear as Shabnam's (Zahra Ahmadi) brother, Tamwar.
Speaking of the extension to her on-screen family, Nina Wadia told DS: "I'm absolutely thrilled Nitin has been cast – he's a fantastic actor. We have both played a husband and wife before. It will be fun having him play my husband in EastEnders.
"It's great working with Nitin as we both speak Gujarati which means we can have a bit of fun on set! He is a good friend. Another good thing about Mrs Masood's great relationship with her husband is that he shows her softer side – with him, you will get to see her smile!"
She added: "I'm also looking forward to working with my on-screen son, Himesh Patel. It's so nice to come to work and have some adult conversation, as at home I spend most of my day chatting to a three-year-old or my three-and-a-half-month-old baby!"
Post Office owner Zainab and daughter Shabnam made their debut appearance on the Square earlier this month.
Both Nitin and Himesh begin filming with the Walford soap next week and are expected to make their first screen appearance toward the end of September, beginning of November.