Southampton City Council has agreed to spend £27m on a office building at the derelict Toys R Us site.
The money is due to come from external borrowing.
It's part of a £150m project for the site which also see 275 flats, new shops, restaurants and possibly a gym.
The scheme was discussed behind closed doors at the council yesterday.
Council officers told the meeting the proposed office building is "about the right size at this moment in time in the market" and it could be a "catalyst generating other office."
But opposition councillors abstained from the vote, saying they wanted to deliver the scheme with 'less risk for the taxpayers.'
Leader of the Council Christopher Hammond described the scheme as a once in a generation opportunity.
The scheme is part of plans to redevelop the so called 'Mayflower Quarter', which the council describes as one of the largest urban regeneration areas in the UK.