Fernando Carro Morillo first appeared in international championships in 2009. At that time he started at the U18 World Championships in Brixen over 3000 meters, where he was eliminated in the preliminary run. Just a year later he switched to the obstacle course. In the spring of 2010 he started in the U20 race as part of the Cross Country World Championships in Bydgoszcz, Poland, in which he did not, however, go beyond 81st place. One year he improved in the same race in his Spanish homeland at the Cross Country World Championships in Punta Umbria to 69th place. In the obstacle course, Carro finished second at the Spanish U20 championships and also qualified for the U20 European championships in Tallinn. Until the championships he did not run a 3000 meter obstacle under 9 minutes. In the final of the championships, he managed to improve his best performance to 8: 54.26 minutes, with which he just missed the podium in fourth. In 2012 he won the Spanish U23 championships over 10,000 meters. In the obstacle course he improved to 8: 35.51 min. In 2013 he started in the U23 age group. In this he became national runner-up and took part in the U23 European Championships in Tampere, Finland in July . He made it into the final, where he finished seventh. Two weeks later he took part in the Spanish adult championships for the first time. In addition to the season's best performance of 8: 40.74 min, he was also fourth. In 2014 Carro was the Spanish U23 champion and also won the U23 Mediterranean Games in Aubagne.
In 2015, Carro improved to a time of 8: 21.78 minutes in July and thus also met the norm for the World Championships in Beijing. In the pre-run he did not get past a time of 8: 38.05 min and was eliminated as seventh of his pre-run. Overall, he finished 14th in his first World Cup participation. A year later he took part in the European Championships in Amsterdam in preparation for the Summer Olympics in Rio . As third of his heat he moved into the finals, in which he reached the finish in ninth. At the end of the same month he was runner-up in Spain and then competed in Rio. In the run-up, he lagged well behind his previous performances and finished in 40th place overall. In the spring of 2017, he again competed in the World Cross Country Championships , this time with the adults. Over the ten kilometers he reached the finish line in 31:24 minutes in 61st place. As in Beijing, he could n't get past the lead at the World Championships in London in August. In 2018, at a meeting in Rabat, Carro was able to improve his best time for the first time since 2015 with a time of 8: 19.30 minutes. In the same month he became the first Spanish champion in the obstacle course. In August he competed at the European Championships in Berlin. After the sovereign entry into the final, he was able to win the silver medal with a time of 8: 34.16 minutes.
In 2019 Carro improved to 41st place at the World Cross Country Championships in Aarhus. In September he was able to successfully defend his national championship title. Before that he ran a time of 8: 05.69 min in a competition in Monaco and has since held the Spanish national record in obstacle course. in October he entered the world championships in Doha for the third time in a world championship competition. This time he made it to the finals, in which he improved again to 8: 12.31 minutes and thus his second fastest time in 2019, compared to the prelim. With this time he took eleventh place at the finish. At the end of the year he finished 20th at the European Cross Country Championships in Lisbon in December.