Blakely (21) joins 14 others in Otago's contracted squad after he gained two brief chances over two seasons in the one-day competition.
Blakely made his debut in March 2013 against Canterbury, snaring the scalps of Rob Nicol and Tom Latham as he took two for 57 from 9.5 overs on debut.
His one game last season was also against Canterbury in March, where he removed Nicol in his spell of one for 26 from four overs.
Blakely was a likely option with the continued unavailability of Blair Soper due to shoulder surgery, and Otago's willingness to contract a local player for the final spot.
Other players added to the list of provincial contracts yesterday were Warren Barnes and Michael Guptill-Bunce (Auckland), Cole McConchie (Canterbury), Dean Robinson (Central Districts), Tony Goodin (Northern Districts) and Matt Taylor (Wellington).