He had to wait until mid-2002 to play his first Test Match, against the West Indies at Grenada. His debut had almost come at Karachi 2 months earlier but the match was abandoned due to bomb blasts near the team hotel. In the Test at Grenada he batted at number 8 and top scored with 107. When it was New Zealand's time to bowl Styris came on and took 2 for 88. The first of his wickets was that of Brian Lara which gave him impressive maiden scalps in both formats of the game. He made an unbeaten 69 in the second innings to complete a dream debut but missed out on the man of the match award which went to Chris Gayle who scored a double hundred.
In the ODI series after the Tests he continued his form but this time with the ball, taking 6 for 25 at Trinidad. This broke the record for best One Day International bowling figures by a New Zealander.
At Mohali in 2003/04 against India he scored his second Test hundred with 119, one of 4 New Zealander's to make a century in the innings. Soon after he made his career best Test score of 170 against South Africa in Auckland, his innings taking just 220 balls.
In June 2004 New Zealand toured England and Styris impressed at Nottingham, making 108. He scored his fifth Test hundred at Auckland against the West Indies, an unbeaten 103 helping his side to win the Test.
When New Zealand chased what was then an ODI record of 322 in 2005/06 against Australia at Christchurch, Styris contributed 101.
He then suffered a back injury missed out on the Sri Lanka series of December 2006. Making his return in the latter stages of the Commonwealth Bank series in Australia and then in the Chappell Hadlee series at home, Styris had done enough to be included New Zealand's World Cup squad.
Styris started the tournament with the man of the match award in a win over England at St Lucia. Chasing 210 for victory, Styris made an unbeaten 87 to guide his side home. His pugnacious batting style and distinctive gait led to former England captain Nasser Hussain referring to him as a "street fighter" from the commentary booth during the game. He made another half century in the game against Kenya and made 80 not out in a successful run chase against the home side. In the Super Eight stage the New Zealanders played Sri Lanka and Styris top-scored with 111 not out. The century came off 152 balls. It was his second ever World Cup century; he scored one in 2003.
Struggle with form in test cricket and subsequent retirement
Shortly after the world cup Styris' form dropped of contributing to injuries and not enough practice due to the injuries. He then participated in a test series against South Africa in 2007 but was dropped from the test squad
Styris aged 35 and competing for a competitive Medium Pace All-rounder slot with Grant Elliott was selected for the Tri-series in Sri Lanka August 2010 he scored 88 runs in the first ODI. Scott Styris completed his comeback by showing a bowling performance in the next match against Sri Lanka when he took the wicket of Kumar Sangakkara However after the tournament he suffered a back stress fracture during training and missed the series against Bangladesh and India. As part of his rehabilitation programme Styris took part and captained the New Zealand team in the 2010 Hong Kong Cricket Sixes. Styris missed the five-match series against Bangladesh as New Zealand were whitewashed 4–0 because Styris was recuperating from his injury. He returned to the team against India in December 2010 and scored 59 in the second ODI to lift the New Zealand total to 258.