Parents travelling on Jetstar domestic flights will now be charged $30 to have their baby sit on their lap, and $50 on Trans-Tasman or international flights.
The new fees, including the rise from $40 to $50 for international baby-carrying journeys, were introduced on Monday and apply to adults nursing children under two. The fees don't affect flights already booked.
Jetstar's domestic fee matches Tigerair's $30 charge for babies travelling on a guardian's lap, in place since 2009.
Jetstar's new fee covers an entire one-way journey - such as Hobart to Melbourne to the Gold Coast - unlike Tigerair which slaps the charge on each leg of a one-way trip.
Qantas and Virgin Australia do not charge a fee for babies (0-23 months) on domestic flights.
A Jetstar spokesman said the new fees also allow for up to four oversized infant items such as a stroller, pram, highchair and portable cot - a bonus not offered by other airlines.
"Like other oversized items, there is additional manual handling and equipment required for oversized infant items like prams," he said on Tuesday.
The $10 hike to international flight fees is also the first increase since 2010.
"We know that fees and charges can be unpopular, but giving customers choice and charging each customer for what they actually need helps us to offer the lowest possible fares, every day," the Jetstar spokesman said.
NURSING BABIES ON AUSTRALIAN FLIGHTS: A BONUS OR A BURDEN?
* Jetstar - $30 for domestic one-way journeys, $50 for Trans-Tasman or international one-way journeys
* Tigerair - $30 for each flight on a domestic one-way journey, no international flights offered
* Qantas - Free on domestic or Trans-Tasman flights, 10 per cent of full fare for international flights
* Virgin Australia - Free for domestic flights, 10 per cent of full fare for Trans-Tasman or international flights