Blackmoore was 21 years old and 10 weeks' pregnant when she died after being viciously assaulted at her home in Wainoni on August 17, 1995. Her 2-year-old son was sleeping in his bedroom at the time of her death.
A 45-year-old man and 47-year-old woman have been charged.
Police charged the man and woman last night and the pair were due to appear at Christchurch District Court this morning.
A $100,000 reward was offered for information on the case in May this year.
When the reward was announced, Blackmoore's partner Laurie Anderson told the New Zealand Herald he was confident the killer would be flushed out.
"It's virtually the same as when it happened," he said.
"It's still raw, you just learn to live with it. It's like a disability – say you lost your arm – you learn to live with your loss."
Detective Sergeant Todd Hamilton said the investigation into Blackmoore's death remained ongoing and detectives were committed to ensuring all those involved were held to account.
"Our thoughts are with Angela's family at they continue to mourn her tragic death.
"Police would like to thank members of the public for information provided following a renewed appeal in May 2019.
"As the matter is now before the court, Police is unable to provide further comment," Hamilton said.
