Ashlee Simpson has thanked her husband Evan Ross for making ''everything so fun'', as they celebrate their fourth anniversary.

The 33-year-old singer married the 'Star' actor - with whom she has three-year-old daughter Jagger - in 2014, and on Saturday (01.09.18), she took to social media to shower her husband with love as they marked their fourth year of marriage.

Posting a picture of the pair as they headed out to dinner, Ashlee wrote on Twitter: ''Happy anniversary my love!! You make everything so fun, and beautiful!! I'm thankful for the day you walked into my life. I love you with all my heart. (sic)''

Evan, 30, also paid tribute to his wife on Twitter when he posted a professional snap of her carrying their daughter, where he stated that marrying the 'Pieces of Me' hitmaker - who also has son Brox, nine, with former husband Pete Wentz - has been ''like a dream''.

The son of Diana Ross wrote: ''HAPPY ANNIVERSARY MY LOVE. You are my life!!! Everyday with you is like a dream! 4 years with the love of my life!!!!!!! Obsessed with u! And thank you for this Angel Baby J. My ladies!! My loves (sic)''

The sweet words come after the pair recently revealed they have plans to expand their brood in the future, once their hectic schedules quieten down.

Asked about the prospect of adding one more to their ranks, Ashlee said: ''It's definitely soon ... in the next year. Definitely in the next year would be nice.''

Fans of the musical couple are set to be in for a treat this month, as they previously announced they will be releasing a new song on every episode of their forthcoming E! series 'ASHLEE+EVAN', which airs in just three days time on September 4.