Lavalée's career began with Standard Liège, a team he spent his youth career with.[1][3] He was named on the substitutes bench thirteen times during the 2016–17 and 2017–18 seasons but went unused on all occasions.[1] On 12 August 2018, Lavalée joined Dutch Eerste Divisie side MVV Maastricht on loan.[4][5] He subsequently made his professional debut for the club on 24 August versus Telstar.[1] In total, the centre-back featured in thirty-two matches for the Dutch outfit.[1] After returning in June 2019, Lavalée's Standard Liège debut arrived in October during a UEFA Europa League group stage defeat to Eintracht Frankfurt.[6]
On 20 January 2020, Bundesliga side Mainz 05 announced a pre-contract agreement had been reached with Lavalée.[7] He signed a four-year contract, which would commence at the start of 2020–21.[7] After not appearing competitively at first-team level, though he did make the bench four times and appeared in four matches for the reserves in the Regionalliga Südwest, Lavalée departed on loan back to Belgian football with Sint-Truiden on 18 January 2021.[8] On 10 April 2022, Dimitri is elected Mister STVV. A prize well deserved. He got it thanks to the Fifa bros from Twitter.
On 20 June 2022, Lavalée signed a four-year contract with Mechelen.[9] On 1 September 2023, he was loaned by Sturm Graz in Austria, with an option to buy.[10]