Rizwan, who also won the PCB's Most Valuable Cricketer of the Year award recently following a stellar year, scored 1326 runs in 29 T20Is at an average of 73.66 and a strike rate of 134.89. He also effected 22 dismissals behind the stumps in the format.
At the Men's T20 World Cup, where Pakistan lost in the semi-finals, Rizwan finished as the third-highest run-getter with 281 runs in six matches. In 2021, Rizwan also became the first batter to touch the 1000-run mark in a calendar year in T20Is, and the 2000-run mark in T20s.
"I want to thank all my team-mates and coaching staff who helped me throughout the year by preparing and training me well enough to contribute to Pakistan's successes," Rizwan said in an ICC statement. "As cricket is a team sport, I would like to dedicate this award to my team-mates and fans."
As for Beaumont, the England opener notched up 303 runs in nine T20Is at an average of 33.66 in 2021, with three half-centuries. She was England's highest run-getter in the year in the format, and was also the third-highest scorer overall. Against New Zealand away from home, she was named the Player of the Series for her contribution of 102 runs in three matches.
She also hit 97 against New Zealand, at home, to help England post their highest T20I total of 184 for 4 in 2021. Beaumont claimed the Player-of-the-Series award then too.
"It's a huge privilege to win the ICC Women's T20I Cricketer of the Year Award," Beaumont said. "I've worked incredibly hard on my T20 game in the last few years. My T20I career has had its ups and downs and I don't think I've always been known for my T20 abilities, so this award gives me a huge amount of confidence.
"As a team we had a great year in terms of T20I results and it feels great to have contributed to team wins. We've got a big year ahead in all formats - with the Ashes, the ICC Women's World Cup and the Commonwealth Games, and I look forward to continuing to work hard alongside my teammates to help us win as many games as possible."
Oman's captain Zeeshan Maqsood, meanwhile, was named the ICC Men's Associate Cricketer of the Year. Maqsood, who bats in the middle-order and bowls left-arm spin, scored a total of 316 runs at 31.60 and picked up 21 wickets at 18.80 across 13 limited-overs matches in 2021.
Maqsood scored valuable fifties against USA and Namibia in ODIs this year. He was especially impressive against PNG, taking four wickets against them twice last year, once in an ODI and the other time at the T20 World Cup.
The Women's Associate Cricketer of the Year award has gone to Austria's Andrea-Mae Zepeda. In 2021, she scored 361 runs in eight T20Is at 51.57 with a strike rate of 102.55. Zepeda was outstanding in the series against Belgium, where she scored a hundred and two fifties in three T20Is. In the first T20I, she hit 101 off 63 balls and shared 111 runs with Busra Uca to guide Austria to a big 197 for 2. Her knock at the top included 17 fours.
South Africa's Janneman Malan has been named the ICC Emerging Men's Cricketer of the Year. He accumulated 715 runs in 17 international matches at 47.66 through the year, including two centuries and three fifties.
Having made his T20I debut in 2019 and in ODIs in 2020, Malan's most noteworthy performance came when he scored an unbeaten 177 - the fourth-highest score by a South African in ODIs - against Ireland in Dublin in July. He followed that up with another hundred against Sri Lanka in Colombo.
Pakistan's Fatima Sana, a seam-bowling allrounder, was named ICC Women's Emerging Cricketer of the Year. Sana, 20, claimed 24 wickets and scored 165 runs in 16 games across ODI and T20I cricket in 2021.
Apart from playing West Indies at home, she also toured South Africa and the West Indies, and played the Women's World Cup Qualifier in Zimbabwe. Her most eye-catching performance came in an ODI in Antigua in July, when she hit an unbeaten 28 off 19 and then took her maiden international five-wicket haul to help Pakistan to a win.