The Liberal Party has announced a $20 million multi-sport expansion of the Joondalup Arena if it is re-elected.

The expansion will include an $11 million new basketball centre and $8 million to build a new home for the West Perth Football Club.

It would also construct 10 more outdoor netball courts and a rugby field.

Joondalup is a marginal seat, held by Labor's Tony O'Gorman by just over three per cent.