Elections to Weymouth and Portland Borough Council were held on 6 May 1999. One third of the council was up for election and the council stayed under no overall control.
After the election, the composition of the council was
| Party | Seats | Gains | Losses | Net gain/loss | Seats % | Votes % | Votes | +/− | |
|---|---|---|---|---|---|---|---|---|---|
| Labour | 6 | -1 | 46.2 | ||||||
| Liberal Democrats | 3 | -1 | 23.1 | ||||||
| Conservative | 2 | +2 | 15.4 | ||||||
| Independent | 2 | 0 | 15.4 | ||||||
