An inquiry heard people were queuing for up to four hours after the first pool game at the Millennium Stadium.
Enterprise and business committee chairman William Graham said the station's "ageing infrastructure" needed "substantial investment".
Great Western Railway said it would work with Network Rail and other train operators to make improvements.
Tournament organisers told the committee in November that delays of up to four hours were "unacceptable".
Great Western Railway apologised for underestimating passenger numbers for the first game in Cardiff - Ireland v Canada on 19 September - calling the situation "embarrassing".
In June, Network Rail unveiled new plans to transform Cardiff Central, although the earliest work could start would be 2019.
Publishing a report on Wednesday, Mr Graham said: "It is clear to the committee that the ageing infrastructure around Cardiff Central Station is not up to the demands of coping with large passenger numbers in a short space of time, such as after a major sporting event.
"Furthermore, we believe those involved in organising transport and crowd control during such events need to work more effectively and use all of the tools at their disposal."
Mr Graham praised steps to ease congestion for the last five of Cardiff's eight Rugby World Cup games.
He said it was imperative lessons were learned before the capital hosts the 2017 Champions League final when "the eyes of the world will be upon us".
Great Western Railway said it was "keen to continue working with Network Rail and other train operators on the Cardiff station improvement master plan, which we hope will tackle some of the infrastructure challenges identified".
Cardiff Central railway station needs an urgent upgrade, AMs have said, after long delays for Rugby World Cup fans.