CAS overturned IIHF decisions that excluded Russia from events in the 2026-27 season, including the men's and women's world championships.
In a brief statement, CAS cited a lack of sufficient evidence to support the IIHF's security concerns.
CAS said its ruling did not address issues such as whether Russia should be required to play without national symbols as a team of neutral athletes, as in some other Olympic sports, or other "organizational consequences."
The IIHF expressed disappointment with the ruling and said it "maintains that its decisions were necessary to protect the safety and security of all participants and safeguard the integrity of its competitions."
"While the IIHF respects the authority of CAS and will act in accordance with its ruling, the outcome does not remove the concerns that informed its assessments."
Russian Sports Minister Mikhail Degtyaryov wrote on the Telegram social media app that CAS "recognized the demands of the Russian Hockey Federation on key points as justified."
The IIHF has barred Russian teams from its world championships since the invasion of Ukraine in 2022. Russia also missed the Olympic hockey tournaments this year.
The ruling is an immediate challenge for new IIHF President Franz Reindl, whose home country of Germany hosts the men's world championship next year.