Feb 5 (Reuters) - Property and casualty insurer Allstate's ALL.N fourth-quarter profit beat Wall Street expectations on Wednesday, helped by strong gains in its underwriting business and higher returns on its investments.

Insurance spending has shown resilience as businesses and individuals continue to prioritize coverage to mitigate risks ranging from natural disasters to health emergencies.

Allstate's consolidated premiums written for the quarter rose 8.8% to $15.06 billion.

The insurer's net investment income also surged, driven by higher returns from its fixed-income securities portfolio.

Insurers typically invest a portion of their cash across asset classes such as fixed-income securities.

Northbrook, Illinois-based Allstate's net investment income jumped to $833 million in the fourth quarter from $604 million a year earlier.

On an adjusted basis, the company earned $2.06 billion, or $7.67 per share, compared with the average analyst estimate of $6.30 per share, according to data compiled by LSEG.

Allstate's underlying combined ratio was 83% in the reported quarter, compared with 86.9% a year earlier. A ratio below 100% means the insurer earned more in premiums than it paid out in claims.

Last week, the company struck a $1.25 billion deal to sell its group health business to insurer Nationwide.

Allstate said it expected losses related to the California fires to be about $1.1 billion, pre-tax, net of reinsurance.

Analysts had expected the insured losses from the California wildfires to be confined mostly to homeowners' insurance businesses at Allstate, Travelers TRV.N and Chubb CB.BN.

Last month, catastrophe risk modeling firm KCC estimated that insured losses from the Los Angeles wildfires could be about $28 billion, making them the costliest wildfires in U.S. history.

Rival insurer Chubb CB.BN said last week it expects a pre-tax net cost of $1.5 billion from the California fires.

(Reporting by Atharva Singh and Arasu Kannagi Basil in Bengaluru; Editing by Shounak Dasgupta)

((Atharva.Singh@thomsonreuters.com))