Sisi was sworn in on June 8, 2014 following a landslide election victory, one year after he ousted Mohamed Morsi, an Islamist who was Egypt's first freely elected and first civilian president.
Sisi "has presided over the flagrant abuse of human rights since taking office a year ago pledging to restore stability," the New York-based HRW said in a statement.
Rights groups accuse Sisi of establishing a regime more repressive than that of ex-president Hosni Mubarak, who was toppled in a 2011 popular uprising mainly against security force abuses.
"Over the past year, Sisi and his cabinet have provided near total impunity for security force abuses and issued a raft of laws that severely curtailed civil and political rights," said HRW.
Signup to our newsletter and follow us on Facebook and Twitter!
Since Morsi's ouster in July 2013, hundreds of his supporters have been killed and thousands jailed. Hundreds have also been sentenced to death after mass speedy trials described by the UN as "unprecedented in recent history".
Overall, Morsi supporters account for nearly half of the 2,600 people to have died in violence since his ouster, along with 700 security personnel and 550 other civilians, Egypt's official National Council for Human Rights said in May.
"Continued silence from the United States and Europe legitimises Sisi's flawed logic that the state's clampdown on its own citizens will yield stability," Joe Stork, HRW's deputy Middle East and North Africa director.
Secular activists who spearheaded the 2011 uprising against Mubarak have also been jailed, over a law banning all but police-sanctioned protests.
HRW said the law was "a de facto protest ban".
Jihadists on the other hand have led attacks targeting security forces, especially in Egypt's North Sinai, bordering the Palestinian Gaza Strip.