[14] Sammy was a member of the West Indies team to the 2002 Under-19 World Cup, which was held that year in New Zealand; he made 22 runs and took three wickets.

Other notable players in that class – just a handful would go on to play senior cricket for West Indies – included Dwayne Smith, Narsingh Deonarine, Carlton Baugh, Daren Powell, and Omari Banks.

In the second innings he recorded his maiden first-class half-century, scoring 53 runs from 70 balls before he was dismissed by spin bowler Mahendra Nagamootoo.

[19] Following a successful domestic season in which Sammy finished as the Windward Islands' second highest wicket-taker in the Regional Four Day Competition with 22 scalps and 261 runs, he was the only uncapped player selected in the 15-man West Indies squad for the NatWest Triangular One Day International Series with England and New Zealand in June 2004.

[21] In September, Sammy was recalled to the senior team in place of 22-year-old Jamaican fast bowler Jermaine Lawson who withdrew from the Champions Trophy squad with a stress fracture of the lower back.

[24] When the West Indies toured India in January 2007 Sammy was included in the squad, with a chance to make his Test debut.

After that set-back, Sammy travelled to England in April and May where he played in the Central Lancashire League ahead of the West Indies' tour of the country in May.

During the 2008/09 Regional Four Day Competition, Sammy played seven matches for the Windward Islands, scoring 476 runs at an average of 43.27 (the second highest for the club that season)[28] and recording his maiden first-class century.

His innings of 121 came from 140 balls and was scored against Barbados who were fielding a bowling line up including Tino Best, Kemar Roach, and Corey Collymore who all had international experience.

[35][36] His career-best Man of the Match figures of 4–26 in the third ODI in Saint Vincent & the Grenadines would have been more flattering still had captain Chris Gayle been able to hold on to a catch that would have given the tall Saint Lucian the distinction of becoming the first West Indian to take a five-fer in every form of the game; he had 5–26 off the same opponents in a Twenty20 International earlier in the series.

Sammy finished the series as West Indies' joint top wicket-taker, himself and Kemar Roach sharing 16 scalps equally.

But eventually West Indies were knocked out of contention when they were drubbed by Australia at Beausejour Cricket Ground in Saint Lucia.

He ended with 51 runs in four innings, the fourth highest aggregate for West Indies, and his 12.75 was the seventh best average.

But as a bowler, his six wickets and average of 12.0 topped the West Indies, and his economy rate of 5.26 runs per over was second.

[38] In the second ODI against South Africa at the Sir Vivian Richards Stadium in Antigua-Barbuda, West Indies appeared well on their way to a second consecutive loss.

But successive run-outs – Denesh Ramdin, Ravi Rampaul and Nikita Miller all went by that route – left Sammy stranded and the West Indies 17 runs shy.

[39] On 17 October 2010 Sammy was named captain of the West Indies Test team for its tour to Sri Lanka and until the end of the 2011 season, replacing Chris Gayle.

[41][42] The previous captain and vice, Chris Gayle and Dwayne Bravo respectively, had chosen not to sign central contracts with the West Indies Cricket Board and were replaced.

[43] Between January 2004 and the start of the tour to Sri Lanka in November, the West Indies had won just five of their previous 62 Tests and were expected to lose the three match series against a team with a good home record.

[54] West Indies lost the second match, drawing the series 1–1; Sammy was his team's second-highest wicket-taker, claiming ten at an average of 17.90.

[58] While playing, Sammy had to deal with distractions from hostile crowds and pundits who criticised his appointment as captain as some believed he could not hold down a place as a player alone.

West Indies lost the Test series 2–0 and Sammy finished as his team's highest wicket-taker with nine at an average of 34.77.

[68] The West Indies entered the final match with a 2–1 lead and a chance to register their first series win against Australia since 1995.

[71] With the West Indies on 13/2 chasing 215 to win from 61 overs on the final day of the second Test, Sammy promoted himself up the batting order to number three to accelerate the scoring rate.

[78] Commenting on Sammy's performance in the series, former West Indies captain Viv Richards said "All of a sudden there was this new-found confidence.

In the journey from group stages to the final, Sammy contributed 27 runs with the bat from four visits to the crease and overall bowling figures of 2/125, and drew a lot of criticism as many people felt he was keeping better players out of the side.

But in the final, when it mattered most, Sammy scored 26 not out from 15 balls and took two key wickets (almost matching his batting and bowling tally for the rest of the tournament) to help his team overcome a slow start and defeat Sri Lanka.

[89] In August 2017, he was named in a World XI side to play three Twenty20 International matches against Pakistan in the 2017 Independence Cup in Lahore.

[94] The Chief Minister of Khyber Pakhtunkhwa, Pervaiz Khattak, offered the all-rounder honorary Pakistani citizenship in response to a special request by Peshawar Zalmi ownership, which Sammy accepted.

[100][101] During the 2020 Pakistan Super League, Sammy was named as Peshawar Zalmi's head coach[102] and he retained the position during the 2021 season.