Neil Patrick Harris thanked his husband David Burtka for ''rocking [his] world'' on their sixth wedding anniversary.

The former 'How I Met Your Mother' stars posted sweet tributes to each other as they celebrated the milestone over the weekend.

Alongside a snap of the pair on their wedding day, Neil wrote on Instagram: ''Six years ago. Perhaps the happiest day of my life. Since then, thousands of memories. No regrets. Thank you, David, for both creating and rocking my world. I am forever #grateful. (sic)''

David, 45, also gushed about how his other half has ''made [his] heart complete''.

He shared another photograph from the special day, and added to his own profile: ''Six years ago today @nph and I got hitched. Thanks for dancing into my heart. I can't believe you stuck around after all these years of me annoying you. You have made my heart complete. Thank you for the best times of my life. (sic)''

The loved-up pair - who have nine-year-old twins Harper and Gideon together - celebrated their anniversary with a dinner date at Topping Rose House in the Hamptons.

The charity dinner was hosted by renowned chef Jean-Georges Vongerichten.

The pair tied the knot at a lavish ceremony in Italy in September 2014.

Neil, 47, and David previously revealed the key to their happy marriage is that they always make ''time for each other'', even if it just involves watching Netflix for a few hours when their schedules are busy.

David said: ''Even if the kids fall asleep and we end up watching Netflix on the couch, that, we feel, is a connection because we're sharing something. Or just cuddling in the morning or bringing each other a cup of coffee.

''It's the little gestures that make up for the bigger stuff.''

He also said the pair are constantly ''working'' on their marriage.

David explained: ''We try to go away or take a date night every so often because I think that's really important, not only for the couple, but for the kids to see.

''The kids see that their parents are safe and their parents are on a good foot. Of course, they don't want you to leave. 'Please stay. Don't go away from us.' But it's important for them to see that we are working on each other because it's another job to cultivate.''