The 29-year-old hit 22 boundaries on his way to 117 on debut for Otago against his former team Wellington on Monday.
Ryder, who averages almost 41 in tests with three hundreds, has been in self-imposed exile from the New Zealand team since early 2012 following a breach of team discipline.
The burly left-hander spent almost a week in hospital in late March after an incident outside a Christchurch bar left him with a fractured skull and rib injuries. He was kept in an induced coma for more than two days.
While recovering from the assault, Ryder was suspended for six months for failing a drugs test for banned stimulants he said he took in a supplement to lose weight.
The ban ended this month and the cricketer with a history of alcohol and disciplinary problems said he would turn over a new leaf in an attempt to break back into the New Zealand team.
Ryder has played 18 tests and 39 one-day internationals for his country.