Malcolm Waller comes from a family of cricketers; his father, Andy Waller, was a former Zimbabwean batsman and his cousin, Nathan, has represented his country at the Under-19 level.

Waller is a middle-order batsman and an off-spinner, who first represented his country at under-15 level in 2000 before finally establishing himself in 2007-08. Good form domestically earned him a spot for the Bangladesh tour in 2008-09. Later the same season, Waller pulled out a remarkable performance against Kenya hitting an aggressive 63 and thus helping Zimbabwe win the series. He hit an even better knock against New Zealand in 2011 when he showed a lot of character and determination with a 74-ball 99 in Zimbabwe's record chase of 329 against New Zealand in a dramatic last over finish.

This strong performance earned him a Test spot against New Zealand in 2011. He remained unbeaten on 72, becoming the 11th Zimbabwean to register a score of 50 plus on Test debut.

In December 2014, Waller was suspended by ICC for suspect bowling action. He remodeled his action, which was found to be legal in August 2015 and he was immediately picked in the national side for Pakistan's tour of Zimbabwe.

Waller featured in Zimbabwe's tour of Sri Lanka in 2017, where the visitors won the ODI series 3-2. Waller contributed 116 runs across 5 innings, making crucial quick runs lower down the order alongside the 4 wickets he took. He also scored 36 and 68 in the only Test that Zimbabwe lost from a position of strength.