With tax-raising powers coming to Holyrood from April 2017, Mr Rennie has made himself finance spokesman - matching Scottish Labour leader Kezia Dugdale, who has already said she will speak for her party on the key issue.
Mr Rennie has also recruited female members from the party, including three councillors, to his leadership team.
He said: “Scottish Liberal Democrats have punched above our weight over the last five years at the Scottish Parliament and the team announced today will help ensure that we continue to lead the agenda.
“Our party is full of talented people and I am delighted that senior party figures outside of Holyrood will play a leading role in driving our policy agenda forwards for the next five years.
“They have contributed a huge amount to the communities they serve, from councillors to campaigners, and bring a wealth of experience to the team.
“This gender-balanced team will provide strong liberal voices inside and outside parliament. These appointments will put the Liberal Democrats in the strongest possible position to grow over the next five years.”
Former leader Tavish Scott will speak for the party on education and sport, while Liam McArthur has been appointed justice and energy spokesman.
New MSP Alex Cole-Hamilton becomes health spokesman, while Mike Rumbles, who returned to the Scottish Parliament five years after losing his seat, will be both the rural affairs spokesman and the party’s business manager.
Carolyn Caddick, a councillor in Inverness, will be the party’s economy spokeswoman, with fellow councillors Eileen McCartin and Karen Clark appointed to speak on culture and social security respectively.
Katy Gordon, who was top of the Liberal Democrat list in the west of Scotland region in May but failed to get elected, is to be chair of the 2017 local election campaign.
Party convener Sheila Thomson will be the children’s spokeswoman, while Scottish treasurer Caron Lindsay takes on social security and Christine Jardine, who stood against Alex Salmond in the Gordon constituency in last year’s general election, is appointed environment spokeswoman.