Simmons is capable of large scores; with three first class double-centuries to his name, but at the same time he has been prone to inconsistency. His career best of 282, in a first-class match for West Indies A against a touring England XI in January 2009, heralded his Test debut in the final Test of that tour. Simmons scored 24 and 8 as the West Indies secured a series-clinching draw at the Queen's Park Oval, Trinidad. Simmons was retained for the following West Indian tour of England, but has played no further Tests.
In April 2014 it was announced that Simmons had been signed by Indian Premier League side Mumbai Indians, replacing Jalaj Saxena. This had the aim of improving the team's fortunes, after they had gone without a win in any of their 4 matches prior to his signing. On 22nd May 2014, Simmons scored his maiden IPL century helping his team post a 7 wickets win over Kings XI Punjab.