The name change, which took effect on 22 September, follows efforts by UK-based joint venture partner Prudential to transition from promoter to investor status in the insurer.
Overall ratings affirmation and stand-alone credit profile upgrade to 'a+' come as the RAA Insurance deal lifts insurer to third in the country's property and casualty market.
Stable underwriting results and a favourable loss ratio in the long-term line underpin the rating as the South Korean insurer pushes further into overseas specialty markets.
The merger is intended to enhance Kyobo Life's digital insurance capabilities by combining Lifeplanet's online platform with its broader life insurance franchise.