The tough-tackling Dragons started brightly at the Stade Aime Giral in Perpignan and opened up an 8-0 lead but Saints hit back to claim a half-time advantage and then powered away after the break.
Yet the Dragons provided a stiff test early on and took the game to their illustrious visitors from the kick-off.
They forced a drop-out early on and Freddie Zitter went close to scoring out wide after combining well with Chris Beattie.
They claimed the lead on 15 minutes as Michael Dobson raced onto a kick through to touch down. He followed up to convert his own score and extended the lead with a penalty on 27 minutes.
Saints responded well but met a determined Catalans defence, Long seeing a dangerous kick well claimed by Justin Murphy and Keiron Cunningham being held short.
Cunningham featured prominently as Saints mounted another counter-attack but Lee Gilmour was unable to force his way over and Murphy again cleared up.
Saints finally hit back on 32 minutes as they found the space to send Graham over and Lyon added the extras.
Heavy knocks forced Catalans forwards Jamal Fakir, Adel Fellous and Pascal Jampy off the field before the interval and Saints took advantage to take a 10-8 lead in at the break.
Long was stopped short after a jinking run but the ball was quickly worked out wide to James Roby and Fa�asavalu went over.
Saints second row Mike Bennett did not return after the break due to a suspected dislocated shoulder but the visitors soon tightened their grip as Long engineered a try for Anderson.
New Zealand winger Anderson rose above opposite number Murphy to claim Long�s high kick and touch down.
Another try followed quickly as Saints took advantage of a contentious penalty for lifting to send Wilkin over.
Dobson thought he had pulled a try back but referee Ashley Klein disallowed his effort for a double movement.
Saints moved up a gear and put the result beyond doubt as Graham created the opening for Long to cross and the scrum-half then kicked high again for Anderson to catch and claim his second.
Catalans were not finished, however, and Aurelien Cologni forced his way over to reduce the deficit and Dobson converted.
Lyon edged Saints further ahead with a penalty but the Dragons ended the game on a high with a last-minute try from John Wilson converted by Dobson.
Catalans Dragons: Guigue, Murphy, Wilson, Hughes, Zitter, Rudder, Dobson, Beattie, Berthezene, Fellous, Jampy, Fakir, Cologni. Replacements: Guisset, Mounis, Martins, Teixido.
St Helens: Wellens, V. Anderson, Lyon, Talau, Hardman, Moore, Long, Cayless, Cunningham, Fozzard, Gilmour, Bennett, Wilkin. Replacements: Roby, Pryce, Graham, Fa'asavalu.
Catalans Dragons: (8) 20. Tries: Dobson, Cologni, Wilson. Goals: Dobson 4.
St Helens: (10) 34. Tries: Graham, Fa'asavalu, V. Anderson 2, Wilkin, Long. Goals: Lyon 5.
Referee: A Klein (London)