The 34-year-old put the Jets 2-1 up in the 41st minute with an emphatic volley past Ivan Necevski in the home goal, after fellow big-name import, opponent Alessandro Del Piero, had cancelled out Ryan Griffiths' 12th minute effort with a trademark free kick.
Heskey had previously scored just one goal in 41 games
Heskey's last goal came for Aston Villa in their 3-1 win over Blackburn in August 2011.
The strike against Sydney ended a torrid run for the Englishman, a record of just one goal in his previous 41 games.
The former Liverpool and Leicester City striker joined the Australian outfit on a free transfer this summer and helped them record their first win of the season against Sydney.
Next up for the Jets is the visit of the Central Coast Mariners to the EnergyAustralia Stadium.