Simmonds came through the
Exeter Chiefs academy, making his debut for the senior side in an
Anglo-Welsh Cup game against
London Welsh in November 2012. He then featured again as a replacement in the final as Exeter defeated Wasps to be crowned champions of England for the first time in their history. Simmonds scored a try in the
2020 European Rugby Champions Cup Final as Exeter defeated
Racing to become champions of Europe for the first time. The following weekend saw Exeter overcome Wasps in the Premiership final to complete a league and European double. At the end of the season Simmonds was named
European Player of the Year. On 20 November 2020 Exeter opened the new Premiership season away at
Harlequins, winning 33–3, with Simmonds scoring three tries – including an outstanding long-range effort – and taking the ‘man-of-the-match’ award. In doing so, he took his try tally in the Premiership to 34 in 49 games – and 47 in 70 games for Chiefs overall. By the end of 2020, Simmonds had scored eight tries in the four Premiership games Chiefs had played, and also scored a try in the Champions Cup game against
Glasgow Warriors. During the Chiefs' match against
London Irish on 18 May, Simmonds scored his 17th try of the season to draw level with the Premiership try-scoring record, before scoring his 18th and 19th tries of the season. Simmonds left Exeter at the end of the 2022–23 season to join French
Top14 side
Montpellier. Simmonds left
Montpellier and joined
Lyon in 2025 ==International career==