Daniel made his professional first team debut and scored his first professional goal against Peterhead on 7 October 2017 in the Scottish Challenge Cup. He scored his first league goal in a 3-1 away loss to Falkirk. MacKay is the youngest player and goalscorer in the club's history, at just 16 years and 174 days.

He bagged his first hat-trick in a pre-season friendly vs Strathspey Thistle on 30 June 2018. Here's hoping he can continue that type of form into the season.

In season 2019/20 Daniel was loaned for the season to Elgin City to gain first team experience.

Daniel returned from his loan spell at Elgin and started v Hearts in the Betfred League Cup game at Tynecastle and has since featured regularly scoring some crucial goals.

In April 2021 Daniel was voted Young player of the year by fans and players and also voted best goal of the season for his brilliant solo effort against Ross County in a 3-1 Scottish Cup win.

Daniel signed for Premiership side Hibernian for season 21/22 to end his time at Inverness after a successful season where he scored nine goals this season and twelve overall in his fifty-seven appearances.

In January 2022 he went on loan to Kilmarnock.

Daniel is back at the Caledonian Stadium for the start of season 22/23 on a season long loan from Hibernian. He is seen as a fringe player at Easter Road and had been loaned out to Kilmarnock last season.