Foreign Secretary Dominic Raab said: "The UK condemns the military coup and the arbitrary detention of Aung San Suu Kyi and other political figures.
"We, alongside our international allies will hold the Myanmar military to account for their violations of human rights and pursue justice for the Myanmar people."
The military took over and detained the nation's civilian leader Aung San Suu Kyi after her party won a landslide in November's elections.
The UK says it will impose sanctions on defence minister General Mya Tun Oo, home affairs minister Lt Gen Soe Htut, and home affairs deputy minister Lt Gen Than Hlaing.
This means immediate asset freezes and travel bans will be enforced against them, as well as further protection, to prevent British aid from indirectly supporting the military-led government.
Instead, the UK government will put in place measures to ensure aid is reaching only the poorest and most vulnerable in Myanmar.
It said: "Myanmar's military and police have committed serious human rights violations, including violating the right to life, the right to freedom of assembly, the right not to be subject to arbitrary arrest or detention, and the right to freedom of expression."
The UK already has sanctions in place against 16 individuals from the Myanmar military.
Thursday's action by the UK is being taken in parallel with Canada, which is also announcing measures against the regime.
The announcements came as protesters returned to the streets of Myanmar on Thursday after a night of armed intimidation by security forces in Mandalay, the country's second biggest city.