That throws into doubt the initiative aimed at tackling gang-violence that killed nearly 5,000 people and forced around 200,000 from their homes in the Caribbean country last year.
On Friday (January 26), High Court Judge Chacha Mwita said that under Kenyan law, the authorities could only deploy officers abroad if a "reciprocal arrangement" was in place with the host government.
The decision to send 1,000 officers to Haiti had been challenged in October by opposition party Thirdway Alliance Kenya.
Its leader is Ekuru Aukot.
"Under the constitution of Haiti, only a legitimately, democratically elected president can actually make such a request to another country, and you all have heard the judge, there's really no reciprocity between us and Haiti."
Haiti first requested help in 2022 as gang violence surged.
But it was unable to find a country willing to lead a security mission.
Many governments have been wary of supporting Prime Minister Ariel Henry's unelected administration.
Previous missions in the nation have also been dogged by human rights abuses.
Kenya stepped forward last July and had hoped to start the mission as soon as this month after getting UN Security Council approval in October.
The government did not immediately comment on whether it would appeal the ruling.
