[6] He hails from San Gavino Monreale in Sardinia, and is known for his climbing ability, which made him a favorite for the Grand Tours.

The following year, he finished second in the Giro d'Italia before taking his only overall Grand Tour win at the Vuelta a España.

Aru went on to finish the Giro in third place overall behind Nairo Quintana (Movistar Team) and Rigoberto Urán (Omega Pharma–Quick-Step), reaching the podium in just his second Grand Tour.

[11] He repeated the feat on Stage 18 finishing at Monte Castrove; he escaped with Chris Froome near the end of the climb and outsprinted his rival.

[14] Greg Henderson accused Aru of faking the ailment, and actually skipping due to a pending biological passport case.

[23] Aru returned to racing at the Tour de Pologne and finished in 5th place as he prepared for his next season target, the Vuelta a España.

It was not until the penultimate mountain day that Aru succeeded, dropping Dumoulin and advancing himself towards his first Grand Tour win.

On the last mountain stage he was not feeling well, and ended up losing 13 minutes to his main rivals, dropping to 13th place in the general classification.

He received no fractures to the knee but it was swollen a lot, and he was recommended by a doctor to stay off the bike for several days in order to recover properly, missing the Giro d'Italia as a result.

One week before the Tour de France, Aru won the Italian National Road Race Championships for the first time in his career.

[30] At the Tour de France, Aru won the 5th stage attacking on the climb to La Planche des Belles Filles, 2.2 kilometres (1.4 miles) from the finish line.

On stage 9 he was accused of unsportsmanlike behaviour after attacking yellow jersey holder Chris Froome as the latter suffered from a mechanical issue.

At the following race, Tirreno–Adriatico, Aru finished 4th to Sarnano Sassotetto, but was struggling on other decisive stages, meaning he once again missed out on the top 10, in 12th place.

Aru could not follow the pace of his fellow Giro d'Italia contenders Chris Froome, Thibaut Pinot, Domenico Pozzovivo, Miguel Ángel López and George Bennett, and ended the race in 6th position.

However, on the following mountain stages, Aru did not manage to finish with the strongest riders meaning that he dropped to 22nd place after the 2nd week of racing.

Aru and his personal coach Paolo Tiralongo made his training too hard, and spent too much time at altitude which meant his body was fatigued already going into the Giro d'Italia.

[38] In March 2019, following a disappointing start of the season, Aru was diagnosed with a constriction of the iliac artery and underwent an angioplasty surgery, which forced him out from racing for several months.

[6] His best results from his final season, were a pair of second-place overall finishes at the Sibiu Cycling Tour and the Vuelta a Burgos.