Richardson opted out of the tournament to be with his wife for the birth of his first child.
"We're thrilled to welcome Adam Zampa in RCB colours. He replaces Kane Richardson. Let's #PlayBold Adam Zampa." RCB tweeted on Monday night.
"The RCB family is excited for Kane and his wife who are expecting the birth of their first child and respect his decision to pull out of the tournament," it added.
Zampa joins the likes of Yuzvendra Chahal, Washington Sundar, Moeen Ali and Pawan Negi, strengthening the team's spin attack.
"We are disappointed to not have Kane's skills with us this IPL, as he was certainly on top of his game," RCB team director Mike Hesson said.
"However, once we found out Kane and Nyki's baby was due during the IPL, it's an exciting time, and we were fully supportive of Kane wanting to be at the birth of their first child.
Hesson felt Zampa also gives the side "extra options if conditions suit spin as expected during the tournament."
This will be Zampa's second stint in the IPL as he earlier played for the Rising Pune Supergiant.
The 28-year-old went unsold at the auction last year while Richardson was bought for Rs 4 crore by RCB.
Both Richardson and Zampa are currently in England as part of Australia's squad for the white-ball tour.
The two teams are slated to play three T20Is and as many ODIs between September 4-16.
The 13th edition of IPL was shifted out of India due to the COVID-19 pandemic.
Let the Truth be known. If you read VB and like VB, please be a VB Supporter and Help us deliver the Truth to one and all.
Belagavi: The state cabinet under the Chairmanship of Chief Minister Siddaramaiah has reportedly given its nod to permit cricket matches at the M. Chinnaswamy Stadium in Bengaluru, subject to certain conditions.
The decision is learnt to have been taken after a meeting held at the Suvarna Vidhana Soudha here on Thursday.
Reports indicate that Home Minister Dr G. Parameshwara has been directed to formulate rules along with a referendum to hold a cricket match at the Chinnaswamy Stadium.
The cabinet’s approval comes subject to conditions, considering the report of Justice D’Cunha, which was prepared after the stampede.
The June 4 stampede during the celebrations for RCB’s maiden IPL title killed 11 people, which raised serious questions over the stadium's capability to host large-scale events.
Will RCB be playing at their home ground next year?
Stating that the “state had learned from the tragedy,” Karnataka Deputy Chief Minister DK Shivakumar on Monday, December 08, dismissed the talks about shifting Royal Challengers Bengaluru’s home games out of the city.
He also said that the Chinnaswamy Stadium is the “pride of Bengaluru and Karnataka” and vowed that IPL fixtures will continue to be played there.
On Wednesday, Shivakumar met the newly elected KSCA president Venkatesh Prasad at the Circuit House in Belagavi and reiterated that cricket matches, including IPL fixtures, will not be shifted out of Bengaluru.
“We have no intention of stopping matches at Chinnaswamy Stadium, but crowd control measures and the Michael D. Cunha committee’s recommendations will be implemented in phases,” he told reporters.
Shivakumar said the government is committed to promoting cricket and supporting fans while safeguarding the state’s reputation, adding that Prasad had sought the government’s cooperation and agreed to work jointly on the issue.

Sep 1: Royal Challengers Bangalore has named Australian leg-spinner Adam Zampa as a replacement for his compatriot Kane Richardson, who pulled out of the IPL starting September 19 in the UAE.