The 34-year-old star, who is expecting a baby girl with her husband, is enjoying the "perfect" holiday, reported Contactmusic.
Keibler flaunted her baby bump in a black string bikini by posting a photograph on Instagram with caption, "Sun, sand and serenity - the perfect babymoon."
Stacy, who split from George Clooney last summer, recently said that she never thought she would get married or have children until she met Jared.
The couple tied the knot in a secret ceremony in Mexico in March and Stacy has no doubt Jared will be a good father.