Exhibit 99 Form 4 Joint Filer Information Name: EnCap V-B Acquisitions, L.P. Address: 1100 LOUISIANA STREET, SUITE 4900 HOUSTON, TX 77002 Issuer & Ticket Symbol: Earthstone Energy, Inc. [ESTE] Date of Event Requiring Statement: 01/07/2021 Relationship of Reporting Person to Issuer: 10% Owner Signature: EnCap V-B Acquisitions, L.P. By: EnCap V-B Acquisitions GP, LLC, its general partner By: EnCap Energy Capital Fund V-B, L.P., its sole member By: EnCap Equity Fund V GP, L.P., its general partner By: EnCap Investments L.P., its general partner By: EnCap Investments GP, L.L.C., its general partner By: /s/ Douglas E. Swanson, Jr., ---------------------------- Managing Director ----------------- Date: 01/11/2021 Name: EnCap Energy Capital Fund VI, L.P. Address: 1100 LOUISIANA STREET, SUITE 4900 HOUSTON, TX 77002 Issuer & Ticket Symbol: Earthstone Energy, Inc. [ESTE] Date of Event Requiring Statement: 01/07/2021 Relationship of Reporting Person to Issuer: 10% Owner Signature: EnCap Energy Capital Fund VI, L.P. By: EnCap Equity Fund VI GP, L.P., its general partner By: EnCap Investments L.P., its general partner By: EnCap Investments GP, L.L.C., its general partner By: /s/ Douglas E. Swanson, Jr., ---------------------------- Managing Director ----------------- Date: 01/11/2021 Name: EnCap VI-B Acquisitions, L.P. Address: 1100 LOUISIANA STREET, SUITE 4900 HOUSTON, TX 77002 Issuer & Ticket Symbol: Earthstone Energy, Inc. [ESTE] Date of Event Requiring Statement: 01/07/2021 Relationship of Reporting Person to Issuer: 10% Owner Signature: EnCap VI-B Acquisitions, L.P. By: EnCap VI-B Acquisitions GP, LLC, its general partner By: EnCap Energy Capital Fund VI-B, L.P., its sole member By: EnCap Equity Fund VI GP, L.P., its general partner By: EnCap Investments L.P., its general partner By: EnCap Investments GP, L.L.C., its general partner By: /s/ Douglas E. Swanson, Jr., ---------------------------- Managing Director ----------------- Date: 01/11/2021 Name: EnCap Energy Capital Fund VII, L.P. Address: 1100 LOUISIANA STREET, SUITE 4900 HOUSTON, TX 77002 Issuer & Ticket Symbol: Earthstone Energy, Inc. [ESTE] Date of Event Requiring Statement: 01/07/2021 Relationship of Reporting Person to Issuer: 10% Owner Signature: EnCap Energy Capital Fund VII, L.P. By: EnCap Equity Fund VII GP, L.P., its general partner By: EnCap Investments L.P., its general partner By: EnCap Investments GP, L.L.C., its general partner By: /s/ Douglas E. Swanson, Jr., ---------------------------- Managing Director ----------------- Date: 01/11/2021 Name: Bold Energy Holdings, LLC Address: C/O ENCAP INVESTMENTS L.P. 1100 LOUISIANA STREET, SUITE 4900 HOUSTON, TX 77002 Issuer & Ticket Symbol: Earthstone Energy, Inc. [ESTE] Date of Event Requiring Statement: 01/07/2021 Relationship of Reporting Person to Issuer: 10% Owner Signature: Bold Energy Holdings, LLC By: EnCap Energy Capital Fund IX, L.P., its sole member By: EnCap Equity Fund IX GP, L.P., its general partner By: EnCap Investments L.P., its general partner By: EnCap Investments GP, L.L.C., its general partner By: /s/ Douglas E. Swanson, Jr., ---------------------------- Managing Director ----------------- Date: 01/11/2021 Name: EnCap Energy Capital Fund IX, L.P. Address: 1100 LOUISIANA STREET, SUITE 4900 HOUSTON, TX 77002 Issuer & Ticket Symbol: Earthstone Energy, Inc. [ESTE] Date of Event Requiring Statement: 01/07/2021 Relationship of Reporting Person to Issuer: 10% Owner Signature: EnCap Energy Capital Fund IX, L.P. By: EnCap Equity Fund IX GP, L.P., its general partner By: EnCap Investments L.P., its general partner By: EnCap Investments GP, L.L.C., its general partner By: /s/ Douglas E. Swanson, Jr., ---------------------------- Managing Director ----------------- Date: 01/11/2021 Name: EnCap Partners GP, LLC Address: 1100 LOUISIANA STREET, SUITE 4900 HOUSTON, TX 77002 Issuer & Ticket Symbol: Earthstone Energy, Inc. [ESTE] Date of Event Requiring Statement: 01/07/2021 Relationship of Reporting Person to Issuer: 10% Owner Signature: EnCap Partners GP, LLC By: /s/ Douglas E. Swanson, Jr., ---------------------------- Managing Director ----------------- Date: 01/11/2021