Hailey Bieber nails garden wedding dress code at Billie Eilish's brother's big day: See photos

Hailey Bieber and Justin Bieber turned heads as the power couple spent some quality time at pal Billie Eilish's brother Finneas O'Connell's big day.

The Grammy-winning producer tied the knot with his longtime love, Claudia Sulewski, on Saturday, August 29, in Montecito, California and the Rhode founder and the Baby singer were among the star studded guest list.

Hailey did her homework and dressed as per the garden wedding dress code, and grabbed attention with her backless citrus-green gown.

Whereas Bieber kept his look formal and sported a three-piece black suit with a crisp white undershirt, along with black shades and his signature hoop earring.

Other famous stars who attended the ceremony were Kristen Bell, Dax Shepard, and Emma Chamberlain, and many more. Eilish’s boyfriend, Nat Wolff, also made an appearance.

The ceremony took place at San Ysidro Ranch in Santa Barbara, with Billie Eilish officiating the outdoor ceremony.

As for the bride's dress, Claudia donned multiple Oscar de la Renta-designed looks throughout the wedding weekend, with her ceremony gown featuring an off-the-shoulder design paired with a scarf-style neckpiece.

"We were putting it on, and I was saying, there’s something about this dress that just demands a moment of silence,” Claudia told Vogue in a final dress fitting ahead of the wedding.