Wadworth & Co Ltd tabled the proposed development for The Millers Pond in Middle Road, Sholing.
The scheme involves replacing the timber outbuilding, laying new decking and putting up a large pergola and a new outbuilding.
Existing play and fitness equipment will be removed.
The planning application was approved by Southampton City Council officers under delegated powers after receiving one objection from a resident.
The objector said the proposal will result in more cars and road safety issues, alongside more disturbance of residents’ peace late into the evening.
A report by planning officers said the scheme would maintain the existing use of the site.
They said: “The proposal together with other potential future promotions to increase the level of trade at the premises can be expected in order to preserve the retention of what some may considered a community asset.
“The proposal may result in an intensification of the premises but not so much as to result in a material change of use.”
A design and access statement prepared on behalf of the applicant by Dolman Building Surveyors said: “The proposal is to transform an area of the existing pub garden to create a more comfortable space for customers that can be used throughout the year.”
Wadworth plans to install rain and wind deflector blinds to the pergola, while glass sliding doors are proposed on the southern end of the structures.
The statement added: “The proposal will not change the use of the site or garden but will enhance the customer experience by providing weather protection for those using the garden.”