Smart/Díaz began their season on the Challenger Series, placing 7th at the 2017 U.S. International Figure Skating Classic and 4th at the 2017 Autumn Classic International. Making their Grand Prix debut, the two placed 6th at the 2017 Skate Canada International in October. In December, they placed 5th at the 2017 CS Golden Spin of Zagreb, scoring 4.18 points less than Hurtado/Khaliavin. Later that month, they won the Spanish national title by a 3.23 point margin, resulting in a final deficit of 0.95 points. On 17 December 2017, FEDH announced that Hurtado/Khaliavin would compete at the European Championships and Olympics while Smart/Díaz would be assigned to the 2018 World Championships. They finished 12th at the event in Milan, Italy.