The 24-year-old becomes Hull’s seventh first-team signing of the summer, joining for a reported £3.5 million, as they prepare for life back in the Premier League.
Stroud has put pen to paper on a four-year deal in East Yorkshire with the club having an option to extend it by a further 12 months.
Primarily a wing-back, he featured in all four of Sweden's 2026 World Cup matches and scored 28 goals and provided 14 assists across a three-and-a-half-year spell with Mjallby.
"I am super happy and super excited to get started here. When I first heard of the interest, it was the only thing I wanted to do," Stroud told the club’s website.
"I spoke with the Chairman and I got an even better impression of the club and everything around it.
"I have individual hopes to play at the highest level possible. When an opportunity like this comes, it's not something you take lightly. To do it here in Hull is a very exciting opportunity.
"It was a dream of mine to play in the Premier League. I am super excited to get this opportunity and hopefully create something magical this season."