Ryan Seacrest Serves as 'Man of Honor' for Sister Meredith's Wedding His sister Meredith got married in Mexico on Saturday.

 -- Ryan Seacrest stepped into one of his most important roles this weekend -- as his sister's man of honor.

Seacrest's only sibling, his sister Meredith, wed Jimmy Leach, according to People magazine. The two exchanged vows in an intimate ceremony in Mexico.

Seacrest, 41, documented his role as his sister's man of honor on social media.

His first duty came Friday night, one day before Meredith's big day.

"[M]an of honor duty #1 – make sure she’s got the dress. check!" he wrote on Instagram next to a picture of him holding up his sister's wedding dress.

On the big day, Seacrest noted that it was "The day your sis grows up," before adding that their "first stop" was a workout.

Seacrest even helped toast the bride before she walked down the aisle with her other six bridesmaids. The TV and radio personality stood out, wearing a blue tuxedo, while the other bridesmaids donned blush floor-length gowns.

In a caption he wrote, "trying to fit in... final countdown!"

After the ceremony, Seacrest congratulated his sister and her new husband. In a caption, he wrote: "Congrats to Meredith on your amazing day and welcome to the family Jimmy."

With Seacrest being Meredith's man of honor Saturday, it was a slight role reversal as usually Meredith works for Seacrest. She serves as the executive director and COO of his foundation, the Ryan Seacrest Foundation.