A man has been jailed for at least 13 years after a toddler was mowed down and killed in Sydney's north-west, a sentence which has remained a secret until now.

Christopher Chandler careered through the fence and into the Constitution Hill backyard where 17-month-old Tateolena Tauaifaga was playing in January 2015, while being followed closely by police.

Chandler's sentence and identity had been the subject of a non-publication order to protect his trial on armed robbery charges, but that was lifted today after the 26-year-old pleaded guilty.

Tateolena Tauaifaga was killed while playing in a Constitution Hill backyard. Picture: AAP (AAP)

Chandler drove on the wrong side of the road and swiped another driver as he fled. Picture: 9NEWS (9NEWS)

9NEWS has also obtained never-before-seen dashcam which shows the then 22-year-old ice addict making his escape after the fatal collision.

His tyres smoke as he rounds a corner in front of a police car and leads the officers down the Cumberland Highway at speeds of up to 140km/h.

Over the next 10 kilometres he veers onto the wrong side of the road, side swipes another driver and spins so he is face to face with the police car before he takes off again.

The Supreme Court heard he screamed at his passenger "f--- I don't want to go back to jail".

Christopher Chandler is also awaiting sentencing on armed robbery charges. Picture: AAP (AAP)

Dashcam video shows Chandler escaping after the fatal collision. Picture: 9NEWS (9NEWS)

At a sentence hearing, his victim's mother Helena Tauaifaga wiped away tears as she told the court her little "mini-me" had just learned to say "I love you mum".

"I'd give almost anything to see her beautiful face again, to be able to play with her, dance with her, comfort her," Ms Tauaifaga said.

Chandler also apologised.

"I was scared ... I messed up so badly and took the life of your beautiful baby girl," he said.

"I do not deserve my life. It is worthless and meaningless.

"I wish I could change what has happened."

Tateolena had just learned to say 'I love you mum' when she was killed. Picture: 9NEWS (9NEWS)

The yard where the 17-month-old was fatally run down. Picture: AAP (AAP)

Ms Tauaifaga said her daughter's death could have been prevented.

Justice Peter Johnson said while the career criminal had a tough childhood, his crime was of the most serious level.

"A little child died because the offender chose to use the vehicle he was driving as a battering ram to enter private property to assist his escape from police in the course of a desperate and self-obsessed course of conduct on his part," Justice Johnson said.