Although the 2018 Super Rugby season proved to be a mixed season for Savea, Savea performed well against France during the mid-year Steinlager series, with his performance in the first two tests including an outstanding try. Due to Sam Cane's ongoing poor discipline, Savea earned a start at openside flanker during the final test of the series, on 23 June 2018. Although the All Blacks defeated France 49-14 in the third test, winning the series 3-0, it proved Savea to be luckless, with Savea coming off injured in the 16th minute, with Matt Todd replacing Savea. Savea missed the 2018 Super Rugby playoffs due to injury.
Savea recovered from his ankle injury in time for the 2018 Rugby Championship, replacing Sam Cane off the bench in both Bledisloe Cup tests against Australia. Savea's dominance over Australia earned him a start against Argentina's Los Pumas for round 3 of the competition, on 8 September 2018. Savea lasted the full 80 minutes against Los Pumas, with the All Blacks winning 46-24, but Savea only earned 12 minutes against South Africa's Springboks the following week. Although Savea only played for 12 minutes during the All Blacks' 34-36 shock loss to South Africa, he still played well and scored a try.
For round 5 of the 2018 Rugby Championship, with Kieran Read being rested, Savea was scheduled to be used as impact off the bench for the All Blacks as usual, with Luke Whitelock starting at number 8 in Read's absence, on 29 September 2018. Savea, however, was drafted into the starting lineup only hours before the test against Los Pumas, with Whitelock falling ill. Savea went on to dominate his opposite number 8, Javier Ortega Desio, winning the first "Man of the Match" award of his international career. Savea lasted the full 80 minutes, with the All Blacks beating Los Pumas 35-17. Savea played outstandingly the following week, in the second test against South Africa, when he replaced the injured Sam Cane only 36 minutes into the test. Savea challenged the Springboks well as scored his seventh career try in the final minute. Savea's try was converted by first-five, Richie Mo'unga, who won the test for the All Blacks through the kick, making the final score a 32-30 win.
His older brother is his former Hurricanes and All Blacks teammate, Julian, who currently plays as a wing for Hurricanes. Savea has Samoan ancestry and is a father-of-one, having married his partner, Saskia, in 2018.