The 33-year-old English actress and 36-year-old American actor attended the New York premiere of Krasinski's movie The Hollars just two months after welcoming their daughter Violet.
Blunt was all smiles in a white David Koma dress with geometric cutouts and a pair of metallic sandals. Krasinski, who directed and stars in the film, wore a simple black suit and tie.
"All the clichés of parenting are true and you feel all sorts of new things," the actor told Entertainment Tonight at the premiere. "It was really this new existential magnet that you feel draw to your family."
Blunt and Krasinski married in Como, Italy, in 2010 after more than a year of dating. The couple, who are also parents to 2-year-old daughter Hazel, welcomed Violet in June.
"She's amazing," Krasinski said of his elder daughter. "She really loves the baby and I think there is this idea of, 'Oh my God, she is adorable.' I mean, when a two-and-a-half year old hugs a newborn baby, it's one of the cutest things you will ever see."
The Hollars co-stars Sharlto Copley, Charlie Day and Anna Kendrick and opens in theaters Aug. 26. Blunt is slated to star in The Girl on the Train and Disney's Mary Poppins sequel, Mary Poppins Returns.